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New gas boiler sizing (39 Posts)
New gas boiler sizingHi all, hoping to get some help on sizing a new gas boiler for my house. My current system is a Utica bc4t oil fired boiler installed in 2008. Sized at 196,000 btu input and 165000 btu output. DHW is also provided through the boiler. The boiler says 143000 water heating capacity. A little background on the house. Built approximately 1930-1935, I live in one half of a double home. The home is approximately 1350 square feet of heated living area, along with an unheated basement at approximately 480 square feet. Living space is heated by fin tube baseboard.
The home is not well insulated. No insulation in the walls, most of the windows are replacement double glazed. All other windows are what I believe to be original to the house, single pane with storm windows. Wall cavities above the sill plate are stuffed with fiberglass bats.
The system is split into two loops both connected by one pipe to the boiler output. 1 loop is for the first floor, and the second loop is for the 2nd floor and finished attic. First floor loop has approximately 55 feet of baseboard, and the second and third floor loop has ~ 67 feet.
I'm having trouble getting contractors to give me estimates. I've had three in the house in the past 2 months and only has sent me a proposal which is way out of price range for a utica svb4 and a 40 gal indirect tank. The other 2 I have called multiple times since they were here and I have not had any luck getting them to send me a proposal. I don't believe that any of them have done a heat loss calc on my home.
I've used the slantfin heat loss calculator myself and have come up with about 77k btu/hr, but that seems quite high for the size home compared to some posts I've been reading on here over the past 2 months. I'm not sure about some of the terms and some of the construction of my home, so I can't be completely accurate myself.
Any help/advice/comments would be greatly appreciated as I'd like to get a new system installed before the winter and take advantage of the installation rebate that the gas company is offering.
Pictures of my current setup/piping and any other information on the home that I can give I will be more than happy to provide.
Thanks in advance,
WhereAre you from?
What kind of area do u live in.
If you had three guys and no one came back there has to be a reason why?
Square feetIs the boiler serving both residences ? Is the square feet stated the entire load this boiler is expected to serve ? Where are you located because the load calc sounds high , 57 BTU per foot is certainly high . If every foot of baseboard installed performed to spec you'd still only be around 70,760 , By the way measuring baseboard and sizing the boiler to that is not a proper heat loss . Please give us a bit more , location is a start too so we can have an idea of possible winter conditions . The way you describe the house sounds like Pa to me . Let us knowYou didn't get what you didn't pay for and it will never be what you thought it would
HeatLuckily you have the whole summer to find the right contractor; one that will perform a heat loss, and analyze the entire system to make sure that you'll be operating as efficiently as possible. Any heat loss numbers that we offer here will be a complete guess.- Joe Starosielec
Guaranteed performance. Guaranteed energy savings.
Serving all of NJ, NYC, Southern NY State, and eastern PA.
locationHome is located in Hazleton, Pa. The boiler serves only my half of the residence. Square footages that were provided are for my half only. The basement area is unheated, but also not insulated from the rest of the house. The other side of the house is also oil fired boiler but they are also installing gas. The partition wall is plaster and lath and uninsulated. Partition wall in the basement is concrete block.
Contractor 1 was a more high technology oriented installer, recommended high efficiency lochinvar and indirect dhw while he was on site May 5.Told me he would get back with an estimate in about a week. Called him 3 weeks later, he claimed he was on vacation and catching up and would have something by the end of that week. I called him back 3 weeks later and he claimed he was busy with all the ac installs going on, and that would he would have something the following day, 2 weeks later and haven't heard from him yet.
Contractor 2 provided the estimate for the utica svb4 and the 40 gal indirect. Estimate was too high.
Contractor 3 was here May 23. He took a look at the chimney to see if it would need to be lined and also discussed an indirect dwh. He said he would need about a week to look into options that would be available to me in my price range. I called him back on June 18 and left a voice mail and have not heard from him since.
I don't think I'm being unreasonable in thinking that I have a pretty straightforward install here and am getting a little frustrated with the lack of attention from contractors. I'm in the mindset now that I may order the equipment myself and have a local one man crew who did a friend of mines install do the the installation for me.
Rich is rightYou nailed it right on the head.
Here's what happened to me last week, since I'm a certified installer for takagi I went to a service call. No hot water, the machine was shot, heat exchanger leaked and it was all over the PC board. It was out dated, also that generation of water heaters was discontinued, the next generation water heaters where discontinued, so now there on there third generation of that water heater.
I gave them a price to do it right, they had it installed for cheaper, it worked less then 24 hours. They called me for service work, obviously i didn't go. Has anyone else have a similar story.
Rich is rightThis post was edited by an admin on July 1, 2014 9:09 AM.
Too high ?How do you know this if you've only gotten one price ? This very well may be the guy who has the knowledge to do the job right . Did you specify what your requirements are , could you tell us your requirements ? I think anyone on here would be hard pressed to imagine that this house needed 57 BTU per foot . Do you have a specific idea in mind about efficiencies and budget for this replacement ? My opinion for what it's worth is that the overall operating efficiency should be of utmost concern due to the fuel being used and a proper installation will go a long way toward this end . Be careful though because there are plenty of guys who will tell you they are the best and they may even have references but if your buying strictly on price those references may not be worth much if those people got a heating system installed based on an unrealistic budget . Yeah he was cheap and we are warm is not a glowing recommendation , a woodstove can keep you warm . Let us know what you are looking for , quality or low cost job . More often than not you cannot have both and if you can you are very lucky indeed . Check the find a contractor bar here on the site , there may very well be someone in your area , I can think of 2 within a reasonable distance from you .
Sounds to me that your heat loss is very high , you have more than enough radiation installed , and could benefit from outdoor reset , only a proper heat loss can verify these things . Peerless (US boiler) is right in Bally also , maybe sourcing a local product can offer some savings . As far as sizing this boiler you should certainly be well below 100,000 unless it's a tree fort .You didn't get what you didn't pay for and it will never be what you thought it wouldThis post was edited by an admin on July 1, 2014 7:12 AM.
PicturesPlease post some photos of the boiler and near boiler piping as well as some photos of the home so that we may get an idea of what you are working with.
just a homeowner here....That being said be careful about the price thing. I will reiterate what Rich said above generally speaking you either get quality or cheap, but almost never get both. If you have set a dollar amount in your head and are trying to hit that number in my opinion you are doing it wrong. I appreciate we (as homeowners) only have so much money to spend, but to be honest I would get a loan if I had to, to make sure the job was done properly. Try and get more quotes, there is a find a contractor link on this site and it can be a good place to start. Don't be afraid to put the search range up to a high number (50 miles) the worst that can happen is they will say no. Many of the good contractors will travel pretty far. Your judgement on what is too high should be based on the estimates you get not on some number you have invented in your head. Heating systems are very expensive (many thousands) in many cases you can get into 5 figures even on a modest house. Find more contractors get as many quotes as you can and personally I would stop chasing after people that don't want to get back to you. If they don't want your business then why would you want them? Good luck with everything!Just another homeowner trying to find his way through.
Switching to gasWhat about putting a new gas burner in the present boiler. That would surely cost less than a new mod con, and you would be warm. When the boiler dies, then a new boiler could use the replacement gas burner.
Any piping problems should be corrected at this time.--NBC
To High?Are you sure the price is too high or is that your budget is to low for a high efficiency system? I don't shop at a Mercedes dealership knowing my wallet only carries the affordability of a Ford or Chevy.
It is not the contractor's job to make the best affordable to you, it's up to you to get the best system you can for the budget you have.
You should be divulging that up front to potential bidders so that you're not wasting their time and they could then provide you a quote based on your budget. There is also nothing wrong with getting multiple quotes from the same contractor for multiple options and make your choice from there."The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
budgetThe first contractor was supposed to provide me a quote on a high efficiency system. With the run around he's been giving me in just getting a quote, I won't be using him that's for sure. The second contractor provided a quote for a mid efficiency system, the svb4 which he claimed in the quote was a high efficiency boiler. For being 2 - 2.5k above my budget, I couldn't justify that expense. The third contractor, I provided a budget to work with and he said it may be cutting close. I told him I could afford to go maybe 1k over what I had in mind. He said he would get back to me in a week after he thought about all the options available to me. I haven't heard back from him and it's been since June 23.
I never said I need a high efficiency system. I would be happy just getting the oil boiler out and a gas one in, and some piping issues corrected. I know I'll save on the heating because I'm sure that the oil boiler is extremely oversized for the house because it was put in no questions asked when the old one failed by the company that supplies the oil. They had no interest in supplying me with something that would save on oil costs. Even though gas prices are rising, it's still cheaper than oil.
I've tried the find a contractor link and i don't get any results unless i put the mileage up to 75. I wouldn't expect a contractor to travel over an hour to give out a quote not knowing if they'll get the job.
I'll get some pictures of the current setup tonight when i get home along with some comments I've been given pertaining to the setup and my current issues that need resolving.
TryGoing down to your local supply house, ask them for a local boiler guy, or go to a boiler manufacture websight and get the phone calls going.
There's other things to consider, like is there parking in your area, sometimes that's a pain. Just thinking out load.This post was edited by an admin on July 1, 2014 5:27 PM.
No disrespect here, but"your local supply house" may not have a clue about proper training and installation practices of their customers. A few do, but the majority in my experience do not. A "local boiler guy" won't cut it either.
RPA members generally have a clue -- I'd start there. The ones they have actually trained know their stuff for sure.
The rep firms are better, especially for certain brands. Viessmann and Triangle Tube come to mind as having well-rounded installer training programs. Lochinvar makes a great product, but I have no direct experience with their training programs.
My local supply houseMy local supply house calls me when he has a problem with an install. Sometimes it's the install,sometimes it can be something else, like a bad board or gas valve.
So I would have to disagree with that my local supply house has to have a good boiler guy that he contacts.
Maybe I am hanging out with good hvac guys.
Also my comment about 140 degree when boiler flue gases condensate. That's my fault it's 140 degree water temp coming back to the boiler.
AgainYOUR local supply house is not in question here.
Referring a homeowner to THEIR local supply house is a complete crapshoot. Qualified hydronics installers have unfortunately become somewhat rare in America. The RPA is actively working to fix that, and a small handful of manufacturers are leading the way.
SnowmeltYou're in NJ right? Where abouts? Curious..."The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
PicsHere are pics of my current boiler. Any questions I will be happy to answer to the best of my knowledge.
The only real current problems that I am having with the system is some occasional water hammer in my domestic supply at the kitchen sink. The other problem is a little worse. The loop that runs the heat on the second and third floor seems to get a lot of air in it. It will be fine for a week or two when it is cold out. If we get a mild day, the following cold snap, the heat on that loop will not heat the rooms nearly as well as it did before the mild day. Then I have to go to the purge valve in the basement on the return line and drain the water until i get no more air bubbles coming out. This can take anywhere from 15 min to an hour. Sometimes near the end of my purge cycle I get a very loud air hissing noise from somewhere around the expansion tank I believe.
WhyIm in middlesex county area.
You won't get cheap from real boiler men.
Z-man hit it on the head.
Take this advice just email the pics to other plumbers before they waist there time getting to the job
BecauseI'm looking to find forward thinking installers in NJ market that might be interested in taking a look at Viessmann."The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
Viessman boilersWales Darby is the reps up there, do you have a unit that's not working correctly.
WalesIs not the rep. If I had a unit not working I'd fix it myself. Been dealing with them since they came to the US. Looking for installers in NJ that might be interested in the boiler line but haven't had the opportunity.
ChrisWhat did you mean by"Looking for installers in NJ that might be interested in the boiler line but haven't had the opportunity."
I'm always looking for boiler work
Where are you from?This post was edited by an admin on July 1, 2014 11:14 PM.
I'm NotJust looking for installers to throw work at. I would never recommend a Viessmann job to an installer that is not a Viessmann Partner unless he was becoming a Viessmann partner.
I'm looking for quality contractors that would be interested in the product line that want to differ themselves from their competition and embrace a product line that gives them a boiler that pretty much nobody in that market is offering. Its gives the opportunity to sell rather then sell against another price for the same boiler.
I have a branch in Brunswick.
BudgetWe don't talk pricing here but I am curious how you came up with a budget.
The cost of getting a system installed is a combination of cost of materials and the contractors labor and profit/overhead. It will vary from region to region depending on local economies.
How in the world did you come up with a budget without a single bid or a system design?
Just because you want something to cost a certain amount does not mean it will. Try going to your local restaurant and telling them you want the lobster diner for $5.
I would suggest you find a reputable contractor and have them design and price a few options. Some will let you pay for the design and credit it back if they get the job. This approach would allow you to get apples to apples price comparisons.
boilerThat boiler doesn't look that old. I think someone mentioned already about putting a gas conversion burner in it as an interim until the boiler needs replaced. Maybe an expert could comment on that and answer this, could a gas conversion be sized to down fire that boiler and work on a new smaller boiler later? Just a thought, but really need an expert that knows about this to comment.Just another homeowner trying to find his way through.
budget and conversionIn my mind, the budget is what I HAVE to spend, money that I have in my possession. Not to sound rude or think I should get a high value system that the contractor will magically fit into my budget, obviously I know thats not the way things work. But when I tell a contractor my budget, and he tells me he can work something up and doesn't get back to me for a month and doesn't return a phone call, what am I to do? There aren't that many reputable names around town, and I've already had 3 in.
So the point being, I just needed an idea if everyone thinks my heat loss sounds reasonable, and what I gather from the comments is that it is not. I don't want a contractor coming in my home, looking at the plate on the boiler and then guessing a number based on me telling him that I think it is oversized. I know it is oversized. 165k is probably 2 to 3 times what I need in this house.
I understand that a company needs to make a profit, and cover their overhead, wages, etc. but I can't see the installation costs on a boiler costing 200% what the cost of the boiler itself is.
The route I will probably take is to try get an accurate heat loss and order the equipment myself, and find a contractor that is willing to install it.
Once I again I appreciate all the help.
SizingTo answer your question about sizing.
The final boiler size needs to be determined by a proper heat loss calc.
To give you a rough idea.You have 122 feet of baseboard. On a really good day they will produce 550 BTU per foot. With most installs you won't get this much. You could not possibly need a boiler with an output rating over 67,100 BTU. There is no possible way to transfer any more energy than that to the rooms.
The most economical choice would be a properly sized 2 stage firing atmospheric boiler that utilizes the existing vent.
Atmospheric boilerHave a look at the Lochinvar Solution, which has an outdoor reset option (may not be useful with your amount of baseboards).
It is a lightweight copper heat exchanger, 2-stage gas valve atmospheric, which will not break the bank, or your back carrying it downstairs.--NBC
WeilmclainThat's what I would install, just need chimney liner, low water cut off , air sepeater expansion tank, B.F.P., pressure reducer, drain and bleed valve.
Permits and a water heater.
I don't think you want an indirect that would cost to much.
A CGA4 with a 40 gallon water heater.
lochinvar solutionSo I've looked at the lochinvar solution. I've also looked into the crown Bali and the veins man Vitodens100. I have a few questions. Would something like the solution or the Bali be able to run an indirect dwh? Also would it be any cheaper to direct vent versus reining the chimney as far as installation costs go? I know in my area I was told a chimney reline would run me about 2k and one of the contractors I had in said it would need to be lined. Is there much of a difference in piping something like the Vitodens100 versus the solution? If it would be comparable costs as far as installation goes, the Vitodens100 can be had for maybe 700 more than the Bali which would be doable considering the fuel savings.
Vitodens VentingYou'd simply drop a 2" Duravent PolyPro Flex or Centrotherm InnoFlue Flex down the chimney. Fresh air can be take from the side or room dependent if you're able.
You can run an Indirect off all of them. Don't know what your DHW need is. You may be able to just add on the CombiPlus DHW unit to the Vitodens 100 and go if 3.5gpm satisfies your need.
You might even want to take a look at the Vitodens 222F while the cost of the unit is considerably more there is NO LABOR for the installation of the Indirect plus it has a lower bottom end at 19,000 btu/hr. Click on the link below...
http://www.vitoteam.com/Pages/eng/sub/submittal.php?b1=B2TA-35&a1=LLH-80&This post was edited by an admin on July 2, 2014 3:19 PM.
Vitodens ventingCouldn't I just run the direct vent right out the wall above the sill plate? I would imagine this would save in materials and labor as well being that there would then be no roof access needed
Not that simplefirst you need to make sure it's safe to do it that way.
Typical requirements are that the pipe must come out of the building at least a foot above the highest recorded snow accumulation in your area, with clearances as much as four feet from windows, doors, inside wall corners etc.
Also, there is much controversy over using PVC pipe for venting these units. Some manufacturers say it's OK to do this, but in general Codes want any venting material to be listed for that purpose. PVC manufacturers haven't done that, and likely won't. There are listed materials but they cost a lot more."Reducing our country's energy consumption, one system at a time"
Steam, Vapor & Hot-Water Heating Specialists
Oil & Gas Burner Service
Baltimore, MD (USA) and consulting anywhere.
dhwForgot to mention, as far as dhw needs, there are only 2 of us in the house with 1 shower, bathroom sink and kitchen.
NavianWhy don't you also consider navian Ncb 240
navienJust curious as to why the recommendation for the 240 over the 180?
YesCan can vent the Vitodens Sidewall in 2" provided as Steam said, you meet all the vent requirements. Viessmann does not allow PVC venting so PolyProp is the most cost effective way to go. The cost is minimal when using 2".
The NCB-180 is only 150,000 btu/hr for domestic hot water. Generally incoming ground temp in the winter is 50 and you want a set point/target temp of 120 so:
150,000/ (70X500) = 4.28GPM. Will that be appropriate enough for your DHW needs?
The btu/hr output ratings on the Navien are for domestic hot water not heating. The on board pump for heating in the NCB can move roughly 5gpm so there needs to be some math done to make sure its adequate to handle your heating needs based off that heat loss. Navien prefers the use of the NCB-240 in the Northeast because of the heating loads, that unit is capable of providing a little more muscle as its 199,000 btu/hr for DHW and you could get 120,000 btu/hr heating out of it. But keep in mind that is not 120,000 btu/hr of 180 degree water.
Until someone does all the math we are all just giving basic information based on a scenario and past experience rather then specific to your project.This post was edited by an admin on July 2, 2014 6:16 PM.