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Large heating bills - where to go from here (34 Posts)
Large heating bills - where to go from hereWe had a $600.00 heating bill for the month of December. I'm looking at making some changes.
Currently this is the set up:
Slant Fin Sentry 210,000/176,000 gas boiler. 98,000 BTU's of cast iron radiators on the first
floor. 3/4 inch pex to a Watts manifold and 1/2 inch pex to the radiators.
A Unico System hot water coil with 25 outlets on the first and second floor. Installed capacity
is 70,000 BTU's. 3/4 inch pex supplies the hot water coil.
There are two zones, one pump. A thermostat on the first floor is dedicated to the cast iron radiators.
A thermostat on the second floor is dedicated to the Unico System.
The house is a 4,500 sq ft. 3-story Victorian built in 1888. The finished 3rd floor is not heated. There
are 10 foot tall ceilings and a large, central foyer with a large, open staircase.
I was thinking about ditching the 210,000 boiler and getting two, high efficiency boilers - one dedicated
to the first floor cast iron radiators with an outdoor reset and one dedicated to the Unico System. The current boiler short-cycles like crazy.
I was also considering under-floor heat to provide some warmth underfoot, though not necessarily shouldering a
significant amount of BTU's.
We had the Unico System installed last year as we bought the house with freeze damage. I knew nothing about HVAC
at that time. It was undersized for the house, so I added the radiators myself this Fall. I'd like to salvage
the Unico System and dedicate it to the second and third floor.
Is this a good approach or should I consider something else?This post was edited by an admin on January 18, 2013 1:55 PM.
2 boilers2 boilers is a way to go, but I would not separate per floor. 2 smaller boilers on a staging control with weather responsiveness would be better
When milder outside temperatures are around, one boiler may be able to do the whole thing, where then two separate boilers would start to short-cycle like you see now with one big boiler.
Heat Loss?:You need to do an accurate heat loss in the entire building, floor by floor and a total. You need to measure all the installed radiation.
Think of your house as a field of meadow muffins. How many bags of meadow muffins will it take to fill it? No matter what you do, it takes "X" amount of bags of meadow muffins to fill it. Consider a cubic foot of gas as a bag of meadow muffins. How much does a bag of muffins cost? Is there excessive use or did the price go up?
The vulture capitalists are getting ready to feed and they might have even started. They bought low, and they are getting ready to sell high. They have legal right to pick our pockets. Its the law.
Be careful. Your ideas could easily cost you. Like stepping over a stack of $100.00 bills to pick up a dime. Or maybe a dollar bill.
How much is a cubic foot of gas, averaged in your bill? That's the total dollar amount, divided by the cubic foot use.
Oil is how many gallons and how much did you pay for it (comparatively).
How many gallons of LP gas did you use in a month?
You didn't say what kind of gas you are using.
Heat lossWe use natural gas. I will be doing all the work myself going forward.
I have load calculations. All 4,500 sql ft of finished living space has a heat loss of 161,636. I also have radiator EDR, which is 98,000 BTU for the first floor.
Unico hot water coil can put out 70,000 BTU max as it's installed, distributed between the
first and second floor. I adjusted the CFM and have it running at 50% of capacity or about 35,000 BTU's. There are no radiators on the
second floor. The Unico System calls for heat infrequently.
I'm rehabbing the house, so things will tighten up as I move along. Currently, there are no storm windows and all the windows need to be rehabbed and weatherstripping added. Lot's of air infiltration that I will be addressing. I will be adding R40 insulation to the attic. Some of the rooms will require gutting and will get insulation where currently there is none.
Because of the layout of the house, the radiators on the first floor are not just heating the first floor. I wish that were the case. We have a 32 ft long x 16 ft wide foyer with a staircase that's 8 feet wide in the middle of the foyer. So the opening over the stairs between the first and second floors is about 8 ft x 8 ft. All the rooms on the first floor are open to the foyer.
98,000 BTU of cast iron radiators on the first floor is plenty. I figure I need only another 55,000 BTUs total for the second and third floors - 25,000 for the second and 20,000 for the third.
Right now though, I'd say 80% of the time, the first floor radiators are calling for heat only. The thermostat on the second floor only occasionally calls for heat. So we have this 210,000 BTU boiler firing for at most 98,000 BTU's of cast iron radiators. The boiler runs for 2-3 minutes and shuts off for 2 minutes, then runs for 2-3 minutes.
I attached a picture of the foyer.This post was edited by an admin on January 18, 2013 4:39 PM.
Why the mismatch?Why was a 200,000 btu boiler installed for the 70,000 btu unico?
For the rads, what temperature did you use for the EDR?
What temperature are you running the system at now? I would pin down the current btu contributions of the unico and rads. It sounds like you have a tremendous heat loss from the first floor to the second and third floors. If that is the case, I think you would be much better served with an underfloor heat system on the first floor, the uniform delivery of heat will reduce the convection currents that are accelerating the loss of heat to the upstairs. If I am correct, only about half your distribution system is forced to heat the whole house. This leads to poor system thermal efficiency and short cycling of the already over sized boiler.
You could keep the rads, but use it as a stage two for faster recovery from setbacks. You would need a system that is capable of handling parallel delivery methods for the same zone, and three different temperatures when you include the unico.
How I got a 210,000 BTU boiler for a 70,000 BTU UnicoWe bought the house with freeze damage, so all the radiators and boiler had burst/cracked. We received a bid for a Unico System AC and heat. This was installed in two phases in 2011. Well, we discovered the Unico System could not heat the house last Winter. The contractor dragged his feet for weeks, we stayed in a hotel one weekend as it was too cold in the house. We also had plastic vapor barriers up to keep heat in one part of the downstairs.
I started reading and realized the contractor made a mistake. As installed, the hot water coil would only produce 70,000 BTU's. This is due to the 3/4 inch pex supply, and also the number of outlets. The maximum amount of BTU's the hot water coil can produce is a theoretical 110,000. You need about a billion outlets, 1 inch pex and and it sounds like a jet plane. I was a newbie to HVAC, unfortunately, and did not know how to salvage what was there. After much back and forth, we agreed there was not enough BTU's in the Unico System to heat the house. He agreed to put in a larger boiler and I then added the radiators myself this fall.
That brings me to this Winter. We now have heat, but huge bills. And I know the boiler is short cycling.
I used a temp of 170 for the radiator EDR.
Could underfloor heat run off the same zone as the radiators?
I'm talking to someone who might sell me their Triangle Tube Prestige Solo PS110 to replace the Slant Fin 210,000 boiler. I was then thinking I could get a small boiler for the Unico and just run the Unico ductwork for the second floor for now. The Unico does nothing for the first floor, except make it feel more drafty.
Where is the return air coming from?Where is the return air coming from for the unico?
complex systemWith that many zones, the mix of radiant and forced air, and the inter-floor convection currents, this system really needs to be properly engineered before you buy or change anything. Changes to coil flows or reconfiguration of supply lines may be necessary to properly balance the system. Especially if you plan on doing the bulk of the work yourself, you really need a set of detailed drawings you can work from. Have you considered hiring a designer?
complex it isThe ideal system would indeed be relatively complex and utilize integration systems that the vast majority of home owners are unfamiliar with. I would heed SWEI's advice and find a designer on heatinghelp to assist you.
Having said that. I'm curious why the unico system was such a massive failure. Is it zoned? Where is it pulling the return air from? Forced air systems really need to be over-sized for the heat loss of the home. Have you talked to Unico?This post was edited by an admin on January 19, 2013 12:20 AM.
Talked to UnicoThe Unico is not zoned. They put in one zone for the whole house. There are two returns: One one the second floor, at the top of the wall where it meets the ceiling, right above the stair landing. The other is on the first floor in the dining room, near the floor.
I talked to Unico a few times. They thought 1 inch pex supplies should have been used, and there should have been two air handlers and hot water coils, one for each floor. They did not think one hot water coil could heat the house.
I think our installer had a lot of experience putting in Unico A/C retrofits, and thought they can just plug in the heating module. Unico has worksheets you can fill out to guide your design. For example, our installer put in two outlets in our foyer. It's 32 ft. by 16 ft, with 10 ft ceilings. Following Unico guidelines, that foyer should have had at least 6 outlets. All the rooms downstairs should've had more than two outlets per room. They also did not study the Unico Heating Module Specification 3660. It has a chart that shows 24 outlets gets you 800 CFM and a max of 86,000 BTU's, if you have a flow rate of 10 GPM. That's a theoretical max, and Unico says don't expect that. Unico says my install likely produces around 70,000 BTU's, evenly distributed between the first and second floors. Last Winter, we had temps downstairs in 40's. We ended up putting .6 mil vapor barrier over those foyer pocket door openings to retain the BTU's in the living room and dining room. We still had to stay in a hotel during some cold spells.
I would rather add radiators to the second floor and abandon the Unico heating module altogether than add a bunch more outlets and another Unico air handler and heating module. The central air works nice, so it's not a total waste. I would like to re-run the ductwork and just have the Unico on the second floor for now, and eventually the third floor. I have the Advanced Control Board, so I can tamp down the CFM to match fewer outlets. The neighbors across the street have a Unico A/C and the installers just put outlets on the second and third floor - no outlets on the first floor.
I am not familiar with using a designer. I've had 5 different HVAC guys out - hydronics guys, Unico guys. Nobody seems to know enough about Unico AND hot water radiators AND the challenges that come with these big old homes.
If the Unico cooling is adequatebut the heating is insufficient, more radiant sounds like the right answer. As you seal and insulate the house, you will probably find the Unico useful for Make-Up Air. I'd leave the first floor outlets until I was absolutely certain they weren't necessary to the final design.
Where are you located?
Total EDR Originally in the houseWe live in Minneapolis.
Everyone says things were oversized in the day and it makes sense, as I can heat the first and second floor just with the 98,000 BTU in radiators on the first floor and the Unico System off, when temps are in the 20 degree range. It feels cool upstairs but temps stay at 68 degrees.
Originally, there was a total of about 180,000 EDR in cast iron radiators for all three floors. About 95,000 on the first floor, 42,000 on the second floor, and 45,000 on the third floor.
We do not live on the third floor at all. It's just used for storage. Eventually, we will use the third floor for home office and family room and guest room. For now, I chose not to heat it. I understand that the joists are not insulated and there will be some heat loss to the third floor ....
As for underfloor heat ... another option I thought about is just dropping a few radiators in the basement to keep the chill off the first floor floors. The floors definitely feel cold underfoot when we have temps in the single digits. You notice it. When family visit there's some whining about feeling cold. There's mortar packed in the rim joist pockets and I plan to knock that out and spray foam.
Would two boilers be the right option with 3 zones, 1 zone per floor? Something that would be modular, in that I could add to an existing system once we were ready to make the third floor livable space.
oversized is goodas it will let you run cooler water temps, allowing a mod/con boiler to really shine. Room-by-room heat loss will tell you what temp at design conditions - be sure to size any additional radiators using the new supply water temp.
In-floor tubing will work better than dangling radiators, but needs its own reset curve. You can do this with onboard controls on better mod/cons, but if both zones are calling for heat at the same time, it's better to use a motorized mixing valve on the RFH zone.
Probably notIn your situation, the system could really take advantage of the latest technologies on the market. A drafty 3 story building is going to require a lot of btu's on the first floor. I would think it would be worth your while to add more zones to this high demand area, otherwise your are forced to overheat rooms that are not experiencing the same heat loss. The overheating acclerates the convective losses into the foyer and up to the higher floors.
At this point, I would not be focusing on the boilers, forget about the triangle tube, leave the unico alone for the moment. A good radiant system should be able to heat the first floor uniformly without the unico, even with the losses to the upstairs, even when the heat is fully shut off to the 2nd and 3rd floors. This is really a function of the distribution system, emitters, and would probably require a good zone manager too.
I would pick up some reading material to get an idea of how this is done and what is popular on the market to achieve this goal. Typically a valved manifold is used in conjunction with an electronic zone manager with matching thermostats. The tstats in each zone communicate with the zone manager, modulating the flow of water. The best systems synchronize the cycling of the zones while regulating the temperature of water produced from the boiler or mixing valves. The end result is a boiler that operates at the lowest temperature possible without short cycling. In your case, I would also be looking for systems that can manage staged control of the hydro coil in the unico. Right now, you have a thermostat dedicated for each system even though they overlap in zones and use a common heat source, that should not be. Likewise, the temperature requirements are different but they are forced to share the same supply water.
Under-floor heatThanks for suggestions. I have some things to think about. I have the Siegenthaler book, but haven't read it cover-to-cover.
Would underfloor heat be worth considering to keep the floor warm, but not necessarily shoulder heating the house? With the controls out there, could we use underfloor heat as a first stage, then the cast iron radiators as a second stage, including the necessary mixing of different temps?
Right now, leaning toward not using the Unico to heat and instead add four radiators (one for each bedroom) upstairs - about 40,000 BTU's. That would total 140,000 BTU's of cast iron radiators for the first and second floor. I would think as we tightened, they would end up oversized, which would enable us to run lower temps.
One reason for not relying on the downstairs radiators to heat second floor bedrooms is the rooms themselves get chilly. We have 3 kids under 4 and doors are always closed for nap time and overnight.
I could probably achieve room-by-room efficiency upstairs with TRV's. Downstairs is so wide open, I'm not sure zoning for individual rooms would get anywhere. The opening between the dining room and living room is 12 ft. wide. The four openings into the foyer are each 6 ft.
Would one modulating boiler work efficiently under this scenario? (under-floor heat and radiators on first and second floor)
Analysis1."The Unico System calls for heat infrequently."
2."A thermostat on the second floor is dedicated to the Unico System."
3."I can heat the first and second floor just with the 98,000 BTU in
radiators on the first floor and the Unico System off, when temps are in
the 20 degree range. It feels cool upstairs but temps stay at 68
Ivanator, based on your description we can pretty clearly see that there is major loss of heat into the higher stories. What I would like to impress upon you is the idea that this bad, and that controlling this problem is the key to your project. This is entirely speculation at a distance though, so take it with a grain of salt.
The original distribution design (95,000 of EDR on the first floor, 42,000 on the second floor, and 45,000 on third) recognized the potential for a significant loss of heat from the 1st floor, not to the outside, but to the higher stories. They did the best they could with the technology of the time to address the issue. I imagine the thermostat for the unico on the second floor is in a common area near the stairwell. It is getting bathed in the heat being lost by the 1st floor, hence explaining why the system is not calling for heat much. Before you installed the rads, the undersized unico ran all out in a hopeless attempt to keep you warm. But even if the hot water coil was capable of delivering enough btu's into the main trunk air ducts, if the distribution is not lopsided to account for the uneven heat loss, you would be forced overheat the 2nd floor. This overheat would accelerate heat losses to the third floor. As you mentioned, the unico really sounds like it was installed with a/c only in mind. And as Unico advised, for heating use, they should have installed two units, a separate system for each floor. It is unfortunate that this was not done, because even if you don't have enough outlets for the required cfm, the zoning would have allowed the system to properly assist your current and possible future hot water rads. As it is now, I can't see how the unico could be utilized for heat on the first floor. But don't rule it out, and if the a/c is good I would leave it alone for the time being and focus on a plan that allows you to heat the first floor with radiant alone.
Let's look more closely at the issues related to the migration of thermal energy between zones within the building. You have three stories with a total heat loss of about 150,000 btu's. Write now you have an EDR of about 100,000 on the the 1st. Hypothetically, let's say you added another 100,000 to each of the 2nd and 3rd floors for a total EDR of 300,000. Also, let's say you replaced your boiler with a 150,000 btu model that is just right for your home's heat loss. Seems like we're golden right? You've got 150,000 firing into 300,000 of EDR. Even if it is not a mod/con we should get relatively low operating temperatures with long cycles. But if you tried this you would find that the upper stories would overheat. The overheat will accelerate the home's natural chimney effect, driving more warm air outside at the upper levels and pulling more cold air in at the main floor. This exacerbates the problem, requiring even more overheat, etc..
Seems like a simple fix though, just split the house up so each floor is a zone and has it's own thermostat. That definitely corrects the overheat and results in a major savings of gas. That's basically the best that could be done until recently. However, there is room for improvement with our hypothetical situation. Since the first floor is shouldering the burden of heating the house, the 150k boiler would be firing frequently into only 100k of EDR. Shortly cycling and higher operating temperatures would be the result; leading to significantly lower system efficiency. Occasionally the upper story zones call for heat too. But if the 1st zone happens to be off we get the same result: 150k firing into only 100k of EDR. A good zone manager will ensure that never happens, eliminating unnecessary cycling and making the best of the current situation.
However, it would be great if the upper zones could pick up their share of the load. That would really improve the mismatch between supply and demand. Unfortunately, the loss of heat from the first floor into the upper floors is preventing us from running the system in the most efficient configuration. Furthermore, because the distribution system is the home itself and not the hydronic lines, the heat on the upper stories is being delivered in an undesirable manner. The bedrooms on the second floor are being heated from the center out. This creates the room temperature problems you noted.
To summarize: Reducing the 1st floor inter building heat loss will result in more even heating on the upper stories, higher operating efficiency, and less short cycling.
Let's look at how this can be accomplished:
1. Most important, stop the draft. Air sealing has always been and will continue to be the most important factor. Not much more to say.
2. Less obvious: convection currents. A distribution system that delivers the heat in a manner that uniformly balances the local demands will create the least convection currents.
"Downstairs is so wide open, I'm not sure zoning for individual rooms
would get anywhere. The opening between the dining room and living room
is 12 ft. wide. The four openings into the foyer are each 6 ft."
This is why you want to zone the first floor. It's counter intuitive, but you do not want the open floor plan to be the distribution system. Right now the space is equalizing because of small differences in temperature. Feels fine but that is not my point. Obviously the open floor plan is creating the path for the heat loss, but it's also subtly masking from you the real btu requirements at a local level. When a space is divided up, one can readily see these requirements. For example, you anticipated the need for TRV's on possible future radiators in the bedrooms upstairs.
Can you see what I'm getting at? To go further, under-floor heat could be utilized in conjunction with the rads. This would be ideal. The underfloor would provide base load while the rads balance the local spots under the windows. In conjunction with the air sealing this is really the best one can do to stall the loss of heat, allowing the upper stairs distribution system to be utilized, hence improving system efficiency and comfort throughout the house.
This is why I would really focus on the particulars of the 1st floor distribution system. Small improvements in that location will pay off exponentially.
With this context, I think you'll see the logic in my answers to some of your following questions:
1. "Would underfloor heat be worth considering to keep the floor warm, but not necessarily shoulder heating the house?" --I would consider using the floor to deliver up to as my btu's as possible in conjunction with the rads to achieve uniformity. Floor warming is an inherit bonus.
2. "With the controls out there, could we use underfloor heat as a first
stage, then the cast iron radiators as a second stage, including the
necessary mixing of different temps?" --Not only can you do mixing and staging, but there are systems that can make use of the rads to balance cold spots during stage 1 operation.
3. "Would one modulating boiler work efficiently under this scenario? (under-floor heat and radiators on first and second floor)" Adding underfloor heat to the first floor would give you much more emitter area in a place that is required to do double duty. The extra emitter area will allow a mod/con to really perform at lower temperatures where thermal efficiency is greatest. However, in my opinion, it is the modulating capability itself that is really the biggest driver of efficiency. Modulation allows all the other tricks like zoning and ODR to work as intended --there is a long list of reasons, both technical and psychological. As for one or two boilers, I would opt for one boiler. It would be easier and less expensive. But two boilers could be configured to provide redundancy.This post was edited by an admin on January 20, 2013 5:50 PM.
Insulation:In my worthless and antique opinion, don't spend another dime on trying to fix this mistake until you insulate the structure and tighten up the windows.
Your Unico heating "Expert" is clueless. If you think that you have problems now, wait until you get done with the massive band-aid being suggested to your problem and then you finally get around to the insulation.
I'm sure that Mr. Unico didn't tell you that he designed the Unico system for an insulated house.
I was taught that you could get 35,000 BTU's reliably from a 3/4" copper line. 3/4" PEX is smaller. I know I'm not a math whiz, but I wish I could wrap my aged brain around 110,000 BTU's out of a 3/4" PEX line.
Trust me, putting Poly up will stop some air infiltration but does squat for heat resistance.
Get insulation blown in or however they can get it in. There's nothing worse than an over radiated and over insulated house that you can't control. Under radiated and under insulated houses are bad because they are cold. But when one room is a sauna and the next is an air base on the Greenland ice cap, you will pay hell to fix it.
Insulate first. Then spend money on your disaster. It might not be as bad then, as it is now.
Just my opinion.
Seen that, fixed that.
Now it makes sense - thanks!Eastman, thanks for your detailed explanation. I had the "lightbulb moment" regarding the open first floor. I've been thinking all along I want as many BTU's as possible downstairs because I will lose them to the second floor. What you're saying is there's a line where excess BTU's will actually make things worse and managing the first floor room-by-room btu requirements should be part of the solution.
It's clear an on/off solution is unworkable for this house and I'm going to have to spend some money to save some money.
We have ungodly amounts of infiltration, by the way. I had a blower door test last year and the guy struggled to even get readings off the front door.
I'm with Ice on this, for sureMaking equipment decisions based upon an envelope you intend to tighten, but have not yet, is really not the way to go. You have heard that old saw about not putting the cart before the horse? Well, this is it! Get the envelope tightened. Create that stable thermal envelope, see how it does, and then make your decisions on heating gear. My old house in MA was not well insulated and had lousy windows. The first year I re-sided, wrapped, re-insulated and put in new, not replacement, windows and there was a profound difference in that house, not only energy wise, but it was quieter in the house as well, with reduced road noise, etc.
Apparently I didn't learn my lesson as the place I moved into here in CA had NO insulation, until I had the place "drilled and filled". Meeting the architect this morning to go over the re-model. Call your utility or local energy auditors to get an analysis of the building and see what you have.
Insulation/infiltrationI agree to an extent. No matter what solution is ultimately deployed, it won't feel warm if there's no insulation - in the attic, for example.
There are two things we're doing this year that will give us the best return. The attic currently has a mix of cellulose and sawdust. We are going to insulate the attic. We have a historical home, so instead of replacement windows, we rehab and weatherstrip and have well-made wood combo storms. Almost as efficient and proven so by the Department of Interior.
As for the walls, there is a 19th century attempt at
insulation - a rough coat of plaster inside the stud cavities. There is
only 1 inch of air space inside the wall. We had part of the house jacked up last Fall. The rooms on that side will be fully gutted as the plaster did not hold - we'll take advantage of that and insulate. But some of the walls in the house (about 25 %) will not get insulation under our ownership, and we plan to be here 20 years.
Appreciate the feedback I've received; helps give me areas to research and possible solutions. This is what I needed.
Boiler Way to BigDon't recall is getting to design temp in December. Not buying the 36 btu/hr per sqft loss. You also cannot sized based on emitter capable btu/hr output. Doubt those air handlers are in 70,000 btu/hr loss areas. Most likely can start a curve where you only need 160 degree water on design day. Best way to solve is either add a buffer tank and outdoor reset to the current setup or just one condensing boiler."The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
Load calcsDesign temp in Minnesota, according the software, is -15. We may see that tonight, but this is a once in every 4 years. And we live in the city, so we have the heat sink.
Big factors in our load calcs are the poor insulation and the number of large windows.
We have 734 sq ft of glass. The windows on the first floor are all 82 inches tall and vary in width from 28 to 40 inches wide. There are four large bay windows on the house as well that are 48 inches wide
The heat loss for the windows totaled 35,760.
This was the Unico installers software - HVAC Learning Solutions. He had not done a load calc until things weren't working. He eventually sent it to me, and once I made corrections the heat loss went from 100,000 to 160,000.
Using the same software, when I add R13 wall insulation to 80% of the walls and R38 insulation for the attic, I bring the heat loss total down to 125,000.
The heat loss also is set for a loose house. If I uncheck loose, heat loss drops to 121,000.This post was edited by an admin on January 21, 2013 2:01 PM.
Have you checked out Green Building Adviser.com? They have a lot of information relating to this subject. Moisture management is something that many people often overlook. I found GBA really does a good job at addressing this problem along with pointing out the particulars of a large variety of building envelope systems. Old houses can have unique problems and it's probably worth your while to get someone on their boards to take a look at your project. (Especially if your dealing with finished attics and masonry.)
I hope my earlier long drawn out explanation doesn't encourage you to jump into a heating system revamp. I agree with icesailor and Jack that insulation/infiltration is the best place to spend your dollars for maximum return. (it just gets boring to talk about) But as you've noted, historical home renovation has it's limits and at the end of day you will still have a 4500 square foot old Victorian in the freezing cold wasteland that is Minnesota.
As you renovate, you'll probably notice that some rooms will overheat while others remain cold depending on what changes you're making to the envelope. Sometimes projects like these go on for 5 or 10 years for a DIYourselfer. People often jump on the aesthetic stuff right away when they move into their knew home; repainting that, refinishing this, adding a light switch here and there. They tend to tackle what they know first, rather then structure, envelope, mechanical, etc. Later they're forced to learn about the other stuff, realizing along the way that they probably wasted quite a bit of time, money, and energy. My advice is to learn as much as you can about the necessary subjects and try to develop an extremely flexible long term master plan, even if it is significantly more expensive. We can't always renovate with perfect planning and eventually your hand will be forced.This post was edited by an admin on January 21, 2013 3:52 PM.
No Way That GlassHas that much of a heat loss. Simple calculation for
Heat loss through and outside panel.
(TI-TO)/R-Value = btu/hr sqft
TI = Temp Indoor
TO = Temp Outdoor"The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."This post was edited by an admin on January 21, 2013 5:26 PM.
window calcs/Triangle Tube 150s Challenger SoloThis assumes a design day of -15, which is Minneapolis. That's what the software chose anyway. Internal temp of 72
Ti - To is 87.
Single pane has an r-value of 1. Double pane an r-value of 2. I have mostly single pane, pr storms missing their own panes. But for my own calcs, I assumed double pane, or storms.
87 x 764 = 66,468 (single pane)
87/2 x 764 = 33,234 (double pane)
If my heat loss will be in the range of 120,000 to 140,000 ( let's assume I make some reasonable improvements, such as attic insulation and some wall insulation) would the Triangle Tube 150s Challenger Solo be a good match?
If my heat loss were 120,000, would the Triangle Tube Prestige 110 Solo be too undersized? I read a post from someone on the wall who had a high efficiency boiler and the input was 10,000 btu's less than his house heat loss and he said it worked perfect.This post was edited by an admin on January 21, 2013 10:02 PM.
Ivanator, what is the duty cycle right now?Ivanator, this is kinda funny, what is the duty cycle right now?
Are you not at design load right now? How is the place heating? What is the on off ratio for your boiler. What is the operating temperature? You don't need software when you are actually experiencing it.
Bad lunches and other points:I have yet to see a heat loss calculator that really covers the real world applications except the old IBR one that you could "fudge". For example, in Massachusetts, Nantucket and Provincetown are listed with a lower factor than Boston or Springfield. It is never colder on Nantucket than it is in Boston or Springfield. However, the wind blows much higher on Nantucket than it does in Boston. So, where the lowest outside temperature found on Nantucket may be 5+, it gets corrected by using Zero (0) as the factor.
The fastest way I have ever found to gauge infiltration loss is another third world method. If the customer is complaining of a cold house and you show up on a day when it is 20+ degrees out, no wind, and the house is at 70 degrees and the circulator is running with the high limit being met, what's wrong? Come back on a day when the house is cold, it is 30 degrees outside and the outside wind velocity is gusting to 30 or 40 and the house won't go over 60, you have an infiltration problem. It doesn't matter how much radiation you add to cover it, it's a silent killer of cash. You say the house is on a list of historic registry and they tell you what you can and can't do. I've seen a lot of these houses. There are things that you can do. Inside storms. but I have seen outside storms. And believe this when I say, a double hung window with an outside storm has more heat resistance than any double pane window you will find. Because of the large air space between windows. Only triple pane will give you a higher rating. That could be double paned sash and an outside storm.
Back in my late teens, I helped a guy shingle the side of his very old two story house. There wasn't more than 2' between his house and the house next door, It was an 1840's house and a lot of shingles had fallen off. There was no paper on the sides. The only things on the sidewalls were lead splines on the window casings. We covered the whole side with 15# felt paper. This old Portuguese old timer who owned the house next door kept walking by and remarking "That house is going to be a lot warmer now". I pondered that for years. Until it dawned on me that the reason was that the paper stopped infiltration.
In Massachusetts, the building codes are nuts about ventilation unconditioned spaces. I see rotted plywood from ice build up ON THE INSIDE because of warm moist air infiltrating through the insulation. I see ice cold ceilings acting as heat sinks and cooling rooms in the winter. Recessed ceiling lights piercing unheated spaces are a real culprit. The most important tool you can own is an infra red thermometer gun. It should me the first tool you grab on a poor heat call. I asked the chief building commissioner about air changes per hour. He showed me that the code called for 18 air changes per hour in bedrooms. A bedroom with two exposed sides is only calculated at 1 1/2 air changes per hour. What factor do you use for that?
If you want to find out where the heat is going or the cold is coming from. Try one of those infra red thermometer guns..
Ignore it at your own peril.
tempsYes, we are at the coldest it's been in something like 4 years. It's -9 or -11 outside depending on your source.
The boiler operating temp is almost 170. The Grunfos pump is on high. The boiler is running constantly and not shutting down. I've monitored the boiler when temps are in the teens, 20's, 30's, and it short-cycles 2 minutes on, 2 minutes off all day long, so this is the first time I've seen it run like this. This must be because the Unico has been running a lot more.
We currently have 2 radiators shut off in rooms we are not using downstairs. These rooms are on the other side of the foyer, and a sectioned off with a vapor barrier. So we are heating with a radiator EDR of 70,000 and a Unico 3660 coil with 24 outlets and 800 CFM, and a water temp of 170. .The Unico specs say that produces about 65,000 to 70,000 btu's. This is assuming the flow through 3/4 pex is 6 gpm I believe. Maybe 3/4 pex can't do that and btu output of Unico is less. I need to get temp gauges and measure at the air handler to see what it's actual output is.
I have a Watts manifold with temp gauges and flow meters that supplies the radiators. The supply temp is 178. The return temp is 140. The flow rate for each line is about .5 to .75. So the total flow for those 7 radiators is about 4.5.
All that comes to about 85,000 btu's off the radiators and supply and return pex. I have about 290 feet of 1/2 inch P-AL-P pex down there. I found a Uponor spec that says 1/2 inch pex loses about 25 btu's per foot, which would put the heat loss at about 7,500 btu's.
The basement itself is only 38 degrees, so pretty cold.
House feels cold downstairs. It was about 69 at 9:00AM at the downstairs thermostat and 72 degrees at the upstairs thermostat. I have the upstairs thermostat set to 74 and the downstairs set to 73, so they're not getting satisfied, and haven't been in 24 hours. So am I safe to assume 140,000-150,000 btu's is holding these house temps in a very leaky house at -10 degrees overnight?
It feels cold downstairs for sure. But as you guys keep pointing that may be due to infiltration. I know we have a very leaky house.This post was edited by an admin on January 22, 2013 1:10 PM.
Yes and no.If the boiler is "holding" 160 degrees with all those radiators shut off, that is all the boiler is capable of delivering. Some here might say that the boiler is too small. You have reached "design temperature" only it isn't designed for that. The loss to the outside is greater than what the boiler can deliver to the inside.. You either tighten up the house or get a much bigger boiler that can maintain 180 degrees or more on a day like you are experiencing. One that can equal the loss to the outside while overcoming the gain to the inside.
Those installers that figured out what you needed with the Unico are clueless and run of the mill airheads that don't understand about heating and heat loss. They are long gone with your cash and you are cold and spending money.
At a minimum, if I had tried to fix the system, I would have at least found out what was in the house before the freeze up and radiators were removed. I would have at least known what the target heat was before I reduced the available heat. I learned long ago that I should never install in a renovation what the owner or GC says he will have in the end. If they cut short, I will be left holding the smelly bag.
If you really work hard at understanding what is going on, you will be far ahead of some others in the field that want to be airplane pilots. They are just winging it. No plane, no license, and no idea of what they are doing.
The only way your heating bills will go down is to increase the resistance of the envelop to heat loss. Adding more heat just wastes more heat.This post was edited by an admin on January 22, 2013 1:06 PM.
Edited posticesailor, I updated the numbers - too many numbers to keep track of with kids underfoot.
Air sealingAs many have said, air infiltration is your biggest enemy. Even if you are not ready to improve the insulation right away, it is amazing what a blower door test and caulk, spray foam and weatherstriping can do to help. Trust me, I've been there.
Air barriers and other stuffI'm really surprised your basement hit 38 degrees. Is it half above ground level?
Another question, have you checked the flues in the the fireplaces? --and any cleanout doors in the basement?
Many people think the r-value of the insulation they're using is the main indicator of performance. One must realize that basically all fibrous batts and other blown in materials are rated in the laboratory using an air barrier on all six sides. This is usually a good assumption for a tightly constructed new building, but drawn out multi-stage renovations typically make it impossible to create a proper continuous air barrier under the siding. (Don't confuse the vapor barrier/retarder bonded to batt insulation with an air barrier --in your climate the vapor barrier needs to be on the inside.) However the plaster layer lends itself perfectly to this. I have bought caulk by the case and successfully sealed rooms to the point you can feel it pressurize with the swing of the door. It's best if you can remove the moldings and seal under them instead of on top of them. Then you are free to use whatever non-paintable caulk you think will last the longest. It's hard to notice air leaks that are sucking heat and moisture *into* the wall, but they're there, closing those off will reduce drafts in other places while preventing condensation from rotting out the wall cavity.
Basements and attics typically allow for major gains without the hassle of disrupting anything else. I would investigate the possiblity of using some type of spray foam or rigid product on the basement walls. (Keep in mind whatever your local code says about fireproofing.) You may also want to put down a thin layer of closed cell foam on the floor of the attic before blowing in the cellulose. The high performance closed cell will create a vapor and air barrier while relying on the more economically wise cellulose to create the needed r-value and fireproofing. (It will also help with thermal short circuits from various penetrations.)
Thanks for the well thought feedbackYou guys gave me much to think about. We've decided to first spend money insulating and addressing infiltration. Attic insulation; spray foam rim joist and other basement issues; insulating rooms scheduled for demo this year; rehabbing windows and replacing missing storm windows.
I'm going to replace the boiler this year as well. I may wait until December to do so. It will likely be a high efficiency boiler.
Check out GBACan't emphasize Green Building Adviser enough for advice on deep energy retrofits and the details of moisture management. Insulation is not a simple topic.