Joined on September 30, 2012
Last Post on June 26, 2014
@ January 31, 2013 2:00 PM in 21st century vacuum/vapor system?Because there have been a number of threads over the years dealing with two-pipe vapor systems, and it sounds like a more or less solved problem.
For example, in the thread Rod linked to, PMJ seems to have really licked the issue. It sounds like he has implemented a modern solution, similar to a superior hybrid of two vacuum control techniques discussed in "Six Kinds of Steam Heat." (Yes that article is for one-pipe but I think the ideas carry over.)
@ January 30, 2013 10:25 PM in 21st century vacuum/vapor system?I feel like a modern vacuum system should leverage higher distribution pressure deltas. The supply and return lines need to shrink to the point where flex copper or composite plastic can be utilized.
I would think such a system should be capable of holding a much harder vacuum. Then perhaps a mod/con can be utilized via some kind of improvised indirect steam generator.
@ January 28, 2013 11:09 AM in Radiant Floor heating? Another questionMany people run tubing in the slab. They don't insulate underneath because they don't intend to use it much which makes the added expense seem pointless. At some point during the winter they try out the slab heat and are disappointed at how long it takes to actually get the room warm. The system is working on it's own schedule and not yours, wasting energy all the way.
I think slab heat can work great in a garage. But it really works best if you only use it to keep the building out of the 30's or 40's all heating season. If you need the garage continuously, crank it up. But for intermittent usage patterns, I suggest paring it with a simple pellet stove for on demand auxiliary heat. Such a two stage system will give you quick response times with minimal btu wasting overshoots. And a mini-split for cooling/heating in the summer/shoulder seasons works great with an open floor plan.
Have you thought about incorporating solar into the system? Utah has some pretty amazing solar radiation levels. Using pellets all year long can be quite inefficient. Lighting solid fuel fires for small demands creates poor combustion efficiency and managing the pellet pile gets old. John Siegenthaler has published a variety of information related to such combination systems that you might be interested in. I also recall reading a posting from someone in Arizona that used a geothermal unit, but instead of pulling heat from the ground it was connected to large water store that was heated with evacuated solar tubes. I would imagine such heat pump based systems could be configured for a/c too.
@ January 27, 2013 8:03 PM in Radiant Floor heating? Another questionFirst, almost certainly the boiler is oversized. If you call them, be prepared to interpret the salesmanship appropriately. However, that doesn't mean there isn't plenty of pellet stoves out there with suitable output ranges for your project.
Second, I suggest looking at building strategies that insulate on top of the slab. This makes the system more responsive. But more importantly, it also makes the wall/floor interface insulation system much more robust. This is particularly important for external steel structures like the one you're considering.
If someone tries to convince you to insulate under the slab because it will add thermal mass, tell them to buzz off. That is an outdated idea promoted to compensate for inadequate insulation, poor window fenestration, and on/off boilers. Build properly and don't buy an on/off boiler. Modern equipment has no problem maintaining 70 degrees 24/7, hence thermal mass internal to the building's insulation envelope is dead weight on the system and tends to be significantly out of sync with the demands of the occupants.
Now, that's not to say thermal mass is all bad. If you were to pile up dirt outside the building's shell, it would be exposed to the full temperature swings of the environment and actually have something to buffer. This would effectively moderate the climate as seen by the structure, reducing peak HVAC demands and creating a more even and comfortable indoor environment.
@ January 27, 2013 5:13 PM in Radiant Floor heating? Another questionBy modulation, I'm referring to the ability to match heating demand with heating supply in a real time manner. If you take a look at modern mod/con boilers, you'll see that the output is variable. Usually the burner is capable of modulating with up to a 5:1 ratio. So if you are looking at a 100,000 btu max output boiler, typically it can automatically adjust itself down to 20,000 btu without occupant intervention. With modulation, the system switches off and on less frequently because there is a very wide zone where supply and demand can be perfectly balanced in real time. This saves major fuel and reduces cyclic wear and tear on equipment.
Correct me if I'm wrong, but the boiler your looking at comes in only one 250,000 btu model. It also utilizes a 90 gallon water jacket. At peak load, 1600 square feet in that climate zone should require at a maximum around 50,000 btu's. I've briefly looked over the Maxim boiler literature; they do not specify a minimum burn rate, but with solid fuels, I have a very hard time believing it could reduce to the range needed for your proposed project. And the 90 gallon water jacket would have to be roughly 10 times bigger to properly buffer such a supply/demand mismatch.
I am not familiar with pellet stoves, but certainly there exists modulating examples with suitable btu outputs. And there is no reason they can't be utilized with floor heat.
Couple of questions:
1. Have you you thought about how you are going to insulate this structure? The building envelope will dictate the size of the boiler.
2. Why a pellet/corn stove? Is this an off grid remote location? Do you want to utilize corn as a combination food/fuel?
@ January 27, 2013 3:41 PM in Radiant Floor heating? Another questionWhat kind of pellet stove are you looking at? Can it modulate the burner output?
@ January 27, 2013 3:21 PM in Radiant Floor heating? Another questionDo you know what climate zone you're looking at? What is the location like?
@ January 27, 2013 3:00 PM in Radiant Floor heating? Another questionHave you posted before? Can you point me to the previous question thread so I can see where we are at?
@ January 26, 2013 5:11 PM in Vacuum air vents on one-pipe systemsHave you made any progress?
@ January 26, 2013 11:24 AM in Large heating bills - where to go from hereCan't emphasize Green Building Adviser enough for advice on deep energy retrofits and the details of moisture management. Insulation is not a simple topic.
@ January 24, 2013 12:48 PM in Large heating bills - where to go from hereI'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.)
@ January 21, 2013 11:12 PM in Large heating bills - where to go from hereIvanator, 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.
@ January 21, 2013 3:51 PM in Large heating bills - where to go from hereInsulation/infiltration
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.
@ January 20, 2013 5:29 PM in Large heating bills - where to go from here1."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.
@ January 19, 2013 2:12 PM in How to control circulator pumps in radiator system with TRVs?I don't quite follow your description. The heat exchanger requires both pumps running to function. If the pump on the open loop only operates while the instant hot water is recharging the buffer, how is heat exchanged continuously into the closed loop system?
Oh wait, you're saying the heat exchanger is inside the tank?
@ January 19, 2013 1:45 PM in Large heating bills - where to go from hereIn 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.
@ January 19, 2013 11:18 AM in Vacuum air vents on one-pipe systemsRight, as a minimum one would need to program a microcontroller board to handle the various aspects of flame control and integration, but these chips are cheap and readily available. As a starting point, I suggest using spare parts from a giannoni style mod/con, substituting our own programmable controller.
@ January 19, 2013 1:50 AM in How to control circulator pumps in radiator system with TRVs?You could use a flow switch.
Where are you located? How many btus does the system need to deliver? Instant hot water heaters are usually a poor choice for a heat source.
**Ignore my answer. I was not thinking about the buffer tank.**
@ January 19, 2013 1:11 AM in Vacuum air vents on one-pipe systemsHas anyone tried this?
Or, why hasn't anyone tried this? (I thought this was done in commercial buildings.) Are we back to the gasket issue?
@ January 19, 2013 1:09 AM in Vacuum air vents on one-pipe systemsBut who makes such a thing. One of us needs to piece together a modulating power burner. In all honesty, we should form a shell company to ask for sample parts from the major players, develop the operating parameters based on the combined experience from this board, then buy the parts in mass and distribute.
@ January 19, 2013 12:11 AM in Large heating bills - where to go from hereThe 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?
@ January 18, 2013 10:51 PM in Large heating bills - where to go from hereWhere is the return air coming from for the unico?