Need some advice on a new condensing boiler install


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Old 12-19-12, 05:56 PM
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Need some advice on a new condensing boiler install

Well, my 1000 year old Burnham oil boiler is about to bite the dust and I'm preparing to replace it with a gas boiler. This will not be a DIY project, although I will be doing a lot of the work with my plumber. With utility company incentives, the cost for a 95% condensing boiler comes to within a few hundred dollars of an 82% cast iron boiler. There are, of course, some issues. My plumber and I have done a number of projects together and, as usual, we are not quite seeing eye to eye. His approach is always whatever is easiest. I have other considerations.
Here is what we have:
The boiler room is in the middle of the house, with a clay lined chimney. The roof is slate, so I don't let anyone but the roofer up there. The plumber thinks we can run a pvc liner in the existing chimney. I've read conflicting information on that, in addition to which I would have to hire the roofer to lower it in. Alternatively he says we can side vent out the 10' to the outside wall, then another 10' to clear the enclosed porch that floats 9' above the ground. The wall it would come out under has all windows about 32" above where the pipe would clear (Forgot to mention- it's a walk out basement). That would put a big, ugly pipe running through my soon to be finished basement. The other problem is that there is no drain in the boiler room.
I want to mount the boiler on a wall outside of the boiler room, leaving the zone valve manifold in the boiler room, along with the to be added indirect water heater. This would have the boiler venting directly out the side wall under the deck, with the pipe running 10' horizontally to clear the underside. It would also put it about 6' from the sump pit, so the condensate could drain there. But a feed and return pipe would have to run from the boiler up to the ceiling, about 15' across to the boiler room, and then down to the manifold. This would run through the unfinished section of the basement, so I'm less concerned about it. Plumber says, "no, you can't do that." I don't see why, so maybe someone here can enlighten me. Or him.

Thanks!
Anthony
 
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Old 12-19-12, 06:19 PM
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You cant drain the condensate in the sump pit as far as I know what code dictates.

Possibly you can tell us the make and model boiler you are interested in, then we can guide you better.

Yes you can vent up a chimney in some circumstances....

There are so many variables. When we know the unit we can help better.

Whats there now?
 
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Old 12-19-12, 06:47 PM
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What's there now is an ancient Burnham oil boiler. The boiler being pitched by the plumber is a Peerless Purefire PF-140, but that's by no means a done deal. If there's something that will better suit my purposes I'm open to it. There is no other drain in the basement. The basement sink (and formerly the washer before I moved it) drained into the sump pit that then pumps the water up to the sewer drain. What are my other options for draining?

Thanks,
Anthony
 
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Old 12-19-12, 07:07 PM
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I don't think draining the sump pit into the sewer is code either... ? Mike, you know that stuff better than me.

The do make condensate pumps for the purpose of moving condensate.

Be sure to use a NEUTRALIZER on the condensate before discharging into any drain that may contain metal piping! Stuff is corrosive and WILL eat the pipe through.
 
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Old 12-19-12, 07:10 PM
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Interesting. In an older home I would expect all drains to have metal pipes.
 
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Old 12-19-12, 07:20 PM
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Yes, me too...

Neutralizers are easy to build. If you google around you can find plans. Not too expensive to buy premade either. Basically just a piece of 4" PVC with threaded cap on top, inlet on the side near the bottom, outlet on side near the top. Fill with marble chips from the garden center... replenish maybe once/twice a year... good to go.

TMB - Plumbing Engineer - Columns: January 2009: Modern Hydronics


image courtesy jjmboilerworks.com
 
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Old 12-19-12, 07:32 PM
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I don't think draining the sump pit into the sewer is code either...
Never seen it allowed from what I know about the code.


Possibly we can list the manual for the boiler in question?
 

Last edited by lawrosa; 12-19-12 at 09:04 PM.
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Old 12-19-12, 08:18 PM
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Peerless® PUREFIRE®
Oh, look. It has a built in neutralizer. That's one problem solved. Interestingly, the link showing the corroding concrete has the condensate just running to a floor drain. In any case, I'd rather not wander off onto a discussion exclusively of the condensate drain. If I can't run it into the sump pit then I'll do whatever code requires. But right now I need to figure out if I can locate the boiler where I want it. If I can't do that I have a whole different set of problems I need to address.

Thanks,
Anthony
 
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Old 12-19-12, 09:00 PM
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The plumber thinks we can run a pvc liner in the existing chimney. I've read conflicting information on that, in addition to which I would have to hire the roofer to lower it in.
 
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Old 12-19-12, 09:44 PM
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Thank you. That tells me that we can't run up the chimney. It is a dual flue chimney and the other flue is used for the fireplace insert. So I can't run a pvc flue that way. What about putting the boiler remote from the manifold and the indirect tank?

I'm open to other units. The Peerless was recommended by the plumber and the local distributor says that he stocks parts for it. A buddy of mine had a Buderus installed. The plumber didn't know the unit and nobody near him could supply parts. It got installed in October and he was getting reliable heat from it in March. So, while I have no attachment to Peerless, I do want to go with a unit I can get serviced properly. Another plumber friend recommended the WM Ultra III, but I haven't had the opportunity to see if there is a local distributor. The company I like does not handle them.

Thanks,
Anthony
 
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Old 12-20-12, 06:28 AM
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You have oil now?

You are going to natural gas?

Have you done a heat loss of the home?

What type of heat emitters?
 
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Old 12-20-12, 06:41 AM
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Working on the heat loss calculations.
Half the house is heated with wood. One room has baseboards to supplement from the wood heat. Two rooms and two bathrooms have cast iron radiators. In the future there will be a master bath that will have radiant and a finished basement half that will probably have wall mounted flat panel emitters. Despite the fact that we heat half the house with wood, I want to size the boiler as if we don't so that it has the capacity to supply the cast iron rads in the remaining two rooms.

Any thoughts on putting the boiler remote from the manifold and water tank?

Thanks,
Anthony
 
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Old 12-20-12, 06:53 AM
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I'm not sure I understand why your guy has objection to 'remoting' the boiler... did he offer any logical reasoning when you asked "Why not?" ... after all, isn't the boiler 'remote' from any of the heat emitters anyway?

I would think that as long as the piping is the proper size for the flow rate there shouldn't be a problem...

Maybe he's not crazy about the 'up and over' design idea? I could see some minor problems with trapped air, but as long as there is proper air removal and flow rate, what would be the issue?

I haven't looked at the Peerless manual yet... take with salt...
 
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Old 12-20-12, 12:54 PM
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I met with the plumber this afternoon. After going around a couple of times he decided that proximity to an exterior wall and a drain was actually a good thing and we could run the pipes back to the manifold. He doesn't like the idea of the indirect being remote from the boiler, as the loop would have to be longer and it's more piping than necessary. But we traced everything around and realized we could actually eliminate a lot of piping by putting the water tank next to the boiler. Also has the advantage of being able to install everything before we tear out the old boiler.
I checked with all three major distributors in my area. All of them carry Peerless. One carries Crown, also. Unless there's a compelling reason not to go with Peerless I would be inclined to go with my plumber's recommendation.

Thanks,
 
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Old 12-20-12, 03:25 PM
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Does your guy understand about "Primary/Secondary" piping, and all the various 'rules' to properly install it?
 
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Old 12-20-12, 03:34 PM
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Yes. He was talking about it today, so I assume he understands it. Possibly a dangerous assumption, but this isn't the first one he's installing, so I hope he has a handle on it.
 
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Old 12-20-12, 03:45 PM
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OK, good... by the 'rules' what I mean is the distance between the tees not being more than 4 pipe diameters, and having at least say 12" of STRAIGHT PIPE both BEFORE AND AFTER the tees.

If you see him install a 90° elbow and then go straight into the closely spaced tees with say a 2" piece of pipe, just say NO!... :NO NO NO:

These 'rules' will NOT be in the install manual.

It would probably be a good idea to be familiar with the rules yourself; check out drawing 6 on this web page:

http://www.comfort-calc.net/primary-..._tutorial.html
 
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Old 12-20-12, 03:45 PM
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I just have to ask..... What wrong with the old boiler????


Take some pics and let us see... You may be able to save oodles of money....


Possible someone only said you need a new boiler when in reality you don't....

Just saying....
 
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Old 12-20-12, 03:56 PM
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Let me ask something else that doesn't seem to have been mentioned... or has it and I missed it?

What is the HEAT LOSS of your home?

The PF-140 is probably more boiler than you need. I would be willing to bet that you could get away with a PF-80...

How was the decision to use the 140 arrived at?

What is the square footage of your home?

Want to do your own heat loss?

Go to the following link and download the Slant-Fin heat loss program... and spend a few hours inputting your data.

Contact Us - P.V. Sullivan Supply Co., Inc.

I think you might be surprised...
 
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Old 12-20-12, 06:04 PM
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Mike-
The old boiler is 50 years old. I was told to replace it when I bought the house 7 years ago. We replaced the burner with a used Riello at that point. Every tech who has serviced it has warned us that it was on borrowed time. Two of them I even trusted. In the past two weeks we have replaced the oil pump and the controller is being held together with spit and a prayer. We get hot water from a coil on the boiler which is corroded. Nobody is willing to try to replace it because they say there's an excellent chance that they will do irreparable damage trying to get it free. Our oil tank is also 50 years old and shows visible signs of fatigue. The solenoid on the burner just started leaking oil. So far this year I've put in 10% of the cost of a new boiler. If I have to replace the controller and the solenoid I'll be at 20%. I think we are at the tipping point now and I'd like to have a new boiler in place before we tip.

I'm not getting a new boiler without a heat loss calculation. This has just been a couple of busy weeks with no time at home not devoted to shop work, so I haven't had the time to take the measurements and do the calculations. None of the questions I've been dealing with here are boiler dependent, although some of them might have influenced the choice of boiler. This project is likely to happen in late January or early February. I'll probably have the heat loss done next week and be able to decide on a boiler then.
 
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Old 12-20-12, 06:42 PM
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None of the questions I've been dealing with here are boiler dependent...
Confused as to what you mean?

Are you not getting what you were hoping for?

If not, what is it that you want?
 
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Old 12-20-12, 07:48 PM
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No, no- I got exactly what I needed. I've always found this to be a helpful place. The participants here have helped me through a few issues over the years. What I meant was that the research that you're helping me with now will be the same, regardless of what boiler or size I get. Where I can locate it and vent it, are the issues I had to deal with. I haven't had time to do the heat loss calculations, but that doesn't mean I can't solve the other problems. I suspect there is a commonality to the venting and placement restrictions.

I'll post back after I do the heat loss calcs for help with sizing the boiler.

Thanks,
Anthony
 
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Old 12-20-12, 07:57 PM
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Gotcha... just checkin... !

I suspect there is a commonality to the venting and placement restrictions.
Absolutely...

and by the way, I didn't like the sound of how close the vent would be to your deck... code enforcement might also have something to say about that. Not to mention what we all say when you have us over for that barbecue...

Check out the install manual for all the "do's and don'ts" of venting locations.
 
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Old 12-20-12, 09:37 PM
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The plumber and I are both checking on the deck proximity. He thinks it won't be a problem, since we'll come out through a former window location (which I'm going to board up and insulate. Who really needs a window in the boiler room?) about 4' off the ground and the deck will be 5' above that. If it is an issue, I think we can go up higher and run horizontally 9' to clear the deck.
 
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Old 01-03-13, 08:49 AM
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Okay, finally got the Slantfin program downloaded and did the heat loss calculation. It came up at 64,129 btu/hr. But I can't figure out how to translate that to boiler size. Is that number the same as the size boiler I need? How do I factor in the 50 gal indirect water heater?
Thanks,

Anthony
 

Last edited by berone; 01-03-13 at 11:48 AM.
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Old 01-03-13, 03:52 PM
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Did you answer the question I had on the square footage of your home? I didn't see it if you did...

I'd like to know, just for a basic 'sanity check' of your heat loss numbers.

I'm gonna take a WAG and say 2600 SQ FT... am I close?

Did you look up the correct 'DESIGN TEMPERATURE' to input for your area? If not, tell me your closest 'big city' and I'll find it for you.

Is that number the same as the size boiler I need?
Yes, on the coldest day of the year.

How do I factor in the 50 gal indirect water heater?
If you look at the specs on the water heater you would like, you will see that there are BTU ratings given. They will ALWAYS be much higher than the heat loss of the home. So a compromise must be taken.

That compromise will be mainly on the RECOVERY TIME of the water heater, meaning that it will take a little longer with a smaller BTU boiler to bring the tank back to temperature after a heavy draw.

Based on only what we know so far, it appears that the PF-80 would be a good match. Yes, you will take a slight 'hit' on the recovery time, but fact is that you might never notice it. Are there Jacuzzi tubs to be filled? Are there 6 people in the home? Did you say you had teenagers?
 
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Old 01-03-13, 04:55 PM
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Good WAG. About 2200 sf. The house is 12" brick with no insulation in the walls, so the factor there is pretty low. I just realized that I hadn't adjusted the factor for the basement floor, and the two rooms that will be over the to be heated basement room. I just fixed that and it dropped the BTU\hr to 58,440.
I'm in Peekskill, NY; roughly between NYC and Poughkeepsie. If I understood correctly, the Design Temperature is 0. No teenagers for another 9 years. There will be one Jacuzzi in a couple of years. I've decided not to make that a factor, though. If the indirect doesn't do the job when we install it, I'll add a small on demand to cover that.
 

Last edited by berone; 01-03-13 at 05:14 PM.
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Old 01-03-13, 06:01 PM
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The house is 12" brick with no insulation in the walls
Red brick? or hollow block?

And I think you said no way to get any in there, didn't you? Plaster walls, right?

In that case I would not size the boiler optimistically. I do think that the 140 is too large, but the 110 might be worth considering in this case.

Zero degrees is playing it safe...
 
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Old 01-03-13, 06:14 PM
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Red brick, yes- no way to get in there. Plaster and lathe over 3/4" fir.
Why would the wall type matter, other than to calculate the heat loss? One of the options in the calculator was 12" brick, firred, plaster over lathe. Yielded .25, same as the new windows. So the numbers are entered correctly (or almost. When I corrected them the total went up to 61,222).
 
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Old 01-03-13, 08:18 PM
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Why would the wall type matter, other than to calculate the heat loss?
My thinking may be flawed... but:

The logic is that you've got that cold, high mass wall staring at you everywhere, just sucking the heat out of the home.

It's my gut telling me that I would want to build a bigger fire is all...
 
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Old 01-03-13, 09:10 PM
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What's interesting is that we have a house that, where the new windows have gone in, is draft free. 12" of brick doesn't allow any air infiltration. I just touched the outside wall and it feels no colder than the interior walls. I think the numbers are the numbers. But let's look at this table from Peerless' website:Name:  Screen Shot 2013-01-04 at 12.03.44 AM.jpg
Views: 939
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If I'm reading this correctly (and please tell me if I'm not) either the 80, 110, or 140 would be acceptable without being oversized. My understanding is that you don't want the minimum on a modulating boiler to exceed your heat loss. The numbers seem to stretch to the upper limit of the 80, so I'm thinking that the 110 would be a better choice. It would leave a bit of overhead and better recovery for the indirect. Am I on the right track here?

Thanks,
Anthony
 
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Old 01-04-13, 02:42 PM
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I was thinking that with all that stone between you and the outside that cold air would pour off the walls much as it does off of a pane of glass.

If your heat loss numbers are correct (and they may well be), then all three are oversized.

No, of course you don't want the minimum above your heat loss... what's the point of buying a modulating boiler in that case?

You want the bottom end of modulation as low as possible in order to take the most advantage of the modulation, while keeping the top end at or slightly above your worst case heat loss. This would seem to make the 80 the only choice out of the three.

And I know you know this, but the more time the boiler spends in the condensing range, the closer you will get to the magic 92-93% AFUE rating. Once you reach a point during the winter that you need greater than say 135° water, condensing is pretty much done and you are back to the AFUE of a conventional non-condensing system.

Most condensing boiler installs are only condensing in the 'shoulder seasons' ... unless more radiation is added to the home in order that the cooler water can achieve heating the home on a 'design day'.
 
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Old 01-04-13, 06:49 PM
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I'm going to review all of my numbers on the Manual J. I'm also going to speak to a third party and see what he would charge to do the Manual J for me.
What determines the water temperature? Does the outdoor sensor adjust that? Or is it set manually?

Thanks,
Anthony
 
 

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