Question about venting a sealed combustion boiler

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Old 12-04-11, 07:33 AM
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Question about venting a sealed combustion boiler

To make a long story short I'm installing my own boiler. Not my first choice but for a variety of reasons this is how it turned out.

This is a 95% efficient 55G modulating gas hot water heater with an indirect coil for the domestic heat. Yes that's in reverse but you'll just have to trust me that it's the right choice for this application.

My issue is that the easiest way to do the PVC intake and vent is to go out through the basement wall and then turn vertical for a foot or two to clear any possible snow drift. The dealer says NOT to do this because of the possibility of condensate freezing in the exhaust line. However the manual that comes with the unit clearly shows that exact scenario as being an acceptable installation.
I've also seen a bunch of installs on job sites now that have rubber boots between the furnace and the PVC. I wasn't thrilled with the idea of gluing pipe to this thing. Are those boots special for gas furnaces or just standard Home Center couplings?

What do you think about the venting?

The other option requires me to punch through a poured concrete ceiling into the living space and then out through the wall. At some point that living space will be remodeled and then I can take it box it all in but for now it would be much easier to go through the basement wall and up.

Thanks for your time -
 
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Old 12-04-11, 02:29 PM
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95% efficient 55G modulating gas hot water heater with an indirect coil for the domestic heat.
Make / Model ? Guessing it's an HTP Versa-Hydro... and if so, technically it's not a 'coil' taking the heat out, it's a brazed plate heat exchanger.

I would go by manufacturers recommendations. And call them if you have any question. Your 'dealer' has good intentions, but may or may not be correct.

Please pay attention to the fact that vent piping needs to be sloped back to the boiler at 1/4" per foot of run in order that condensate will drain back to the boiler and be disposed of. As long as this is done, there is probably no problem with running and elbow and up.
 

Last edited by NJT; 12-05-11 at 04:22 PM.
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Old 12-04-11, 02:51 PM
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My limited experience is with a condensing forced air furnace. For that, the PVC vent line had to be pitched back toward the trap in the furnace. The vent outlet had to be above the maximum snow line, taking into account potential drifting.

All these details should be prescribed by the manufacturer's installation instructions.
 
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Old 12-04-11, 03:00 PM
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I would think the hot exhaust would melt anything that froze from the previous burn. I wouldn't expect anything to accumulate.
 
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Old 12-04-11, 06:06 PM
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You are correct that it's a Versa Hydro PHE 130/55 and of course correct on the plate exchanger. I actually sent you a PM earlier this fall when I knew this was going to be happening to see if I could hire you for a day but you don't accept PMs any more. I tried to go pro but the area rep was a bit of an ass and the neither of the dealers they recommended were willing to travel to the Lehigh Valley. So I rolled the dice in a big way and will be installing it myself. Biggest gamble I've ever taken but I'm cautiously optimistic that everything will work out well.

Below is taken from the manual. They supplied the T with it for the intake but the exhaust in this pic appears to have a mesh cap on it and that I don't think was in the box. but overall that's exactly what I'd like to do with it.

Thanks for all the replies. I've been doing TOO much reading and actually forgot about the slope required. I have to rent the monster SDS tomorrow to put some very large holes from the mechanical room into the main basement and punch the holes for the intake/exhaust. Intake/exhaust should actually be pretty easy as I'm just going to go out where the oil fill pipe was.

 

Last edited by speedy72; 12-04-11 at 06:24 PM.
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Old 12-05-11, 04:23 PM
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Let us know how it works out! ..........................
 
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Old 12-05-11, 06:23 PM
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Will do. I'm sure there will be more questions as well. Got monster holes in today - and will be cleaning up concrete dust for months. What a mess. Gas company comes tomorrow to pull out 95% of what they did three weeks ago and start over. But after tomorrow the unit will be set in place, have gas and electric. I need to get a couple fittings from grainger and then I can start piecing this whole thing together.
 
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Old 12-12-11, 06:21 AM
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Well it's fired up. Just running as a hot water heater and still lots of work to do to get hangers in place, properly run the electric and finish out some ancillary plumbing but it is running. Only problem I see so far is a repeated condition of "temp blocking". Top tank sensor is at the 150 degree target but bottom sensor seems to be stuck down around 75 degrees. Not sure what that's all about. I'll take picture when done but it's coming out pretty nice. Sweat joints don't look great but I took my time to get all the pipes square and level.

Sweating pipes truly is an art. I had zero leaks but way too much extra solder on there. I hate to think how many drops of solder ended up inside the pipes from using too much solder.
 
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Old 12-12-11, 08:38 AM
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Sweating pipes truly is an art. I had zero leaks but way too much extra solder on there. I hate to think how many drops of solder ended up inside the pipes from using too much solder.
It really is... main thing of course is to get the pipes and fittings as clean as possible and not use too much heat.

A general 'rule of thumb' that I like to use on the smaller sizes of pipes, up to say 1" or so, to use as much solder (approximately) as the diameter of the pipe... 1" pipe, 1" of solder... bend a little 'crook' into the solder so you know when to stop feeding.

It's hard at first to get over the feeling that you didn't use enough, ain't it?
 
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Old 12-12-11, 09:45 AM
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Originally Posted by NJ Trooper View Post
It really is... main thing of course is to get the pipes and fittings as clean as possible and not use too much heat.

A general 'rule of thumb' that I like to use on the smaller sizes of pipes, up to say 1" or so, to use as much solder (approximately) as the diameter of the pipe... 1" pipe, 1" of solder... bend a little 'crook' into the solder so you know when to stop feeding.

It's hard at first to get over the feeling that you didn't use enough, ain't it?
I took a basic resi plumbing class at the local votech about ten years ago and all of those little tips came back to me as I was doing it. But it's still more like 3" of solder although granted most of it ends up on the floor I also got a nice little benzo torch with a 5' hose so I can leave the mapp gas tank on the floor. Much more flexibility to get the heat where I want it. I'll try less heat for the ten or twenty that I have to do this afternoon. Trying to finish the heat loop fill pipes and the potable water expansion tank today.

I've noticed the burner kicking on for just a 3 degree drop, which only takes about 25 seconds to recover before it shuts off again. Have to dig into the differential settings on this thing. With a recovery rate of 141GPH there is no reason to be recovering from a 3 degree drop when there isn't actually a call for heat. You could be 15 degrees down when there's a call for heat and it would recover in a minute or two. For that matter I can probably shut off the DHW priority as well considering the 141GPH recovery time.

I have a post here where several of you pretty much wrote a book on differential settings. Time to go back and read that again. Worked great on the oil boiler. Cut consumption down noticeably, especially during the summer.
 
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Old 12-12-11, 11:13 AM
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Originally Posted by speedy72 View Post
Only problem I see so far is a repeated condition of "temp blocking". Top tank sensor is at the 150 degree target but bottom sensor seems to be stuck down around 75 degrees.
Hello Speedy,
I'm not sure about your unit. As far as my super stor goes that is perfectly normal.
The water is typically 140-150 at the top and the cold comes in at the bottom and is usualy around 80*. Only right after a heating cycle and no demand is the water at the bottom hot.

Peter
 
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Old 12-12-11, 05:52 PM
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Please get a local professional in to check the combustion. Mod-Cons are critical in their setup. The manufacturer of the mod-con I am in the process of installing is emphatic about setting up the boiler with an electronic combustion analyzer.
 
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Old 12-12-11, 06:54 PM
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Before





Middle



and after



Getting the combustion done has sort of gotten lost in everything. I have two local shops that might do it but I'm not sure either one has a digital meter or uses it often enough to be good with it. I was told that this unit is factory calibrated to be pretty close and that the high mass units are not as finicky as the low mass like the Elite from HTP.

I'm not going to quit my day job but I'm pretty happy with how it's coming together.
 

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Old 12-13-11, 10:06 AM
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Originally Posted by PeterNH View Post
Hello Speedy,
I'm not sure about your unit. As far as my super stor goes that is perfectly normal.
The water is typically 140-150 at the top and the cold comes in at the bottom and is usualy around 80*. Only right after a heating cycle and no demand is the water at the bottom hot.

Peter
Missed this before. Thanks Peter. This is of the same family as what you have so that's very good to know.
 
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Old 12-13-11, 04:15 PM
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I bet it was loads of fun doing that black steel so close to the ceiling. Good to see you used long radius ells for the venting.
 
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Old 12-13-11, 05:12 PM
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Originally Posted by Grady View Post
I bet it was loads of fun doing that black steel so close to the ceiling. Good to see you used long radius ells for the venting.
that's a long story. I hired the HVAC side of the gas company to put those pipes in. After all there's only so much time in a day and gas line is not something I wanted to do wrong. I paid them very good money to run all that pipe and was very specific that I wanted a crew that knew how to thread pipe, use a tape measure and knew what a right angle was. They completely screwed up the job. It was safe, but it looked terrible and they had not a cut a single piece of pipe, just using lengths off the truck. Supervisor came out and flipped out, picked apart stuff I didn't even care about. So they did 100% of the job over again and added a few things that weren't done before. Actually the only piece of pipe they did't cut to length that they could have is the short piece to the boiler. You can see the couple at the top of the picture. Those poor guys busted their ass that 2nd trip.

At the end of the day they had two things left to do. Cut out a pipe from the old long dead gas service and pressure test everything. You can see the old pipe in the middle picture. When they cut into the pipe gas came pouring out of it. They taped it off but it was a full out response. Evacuated the building, killed power and waited for the utility emergency response crew to show up. Turns out it was just residual gas in the line that had been capped for 35 years but it was VERY exciting for about 25 minutes there.

So the last thing was pressure test and bleed. Now we used the HTP and ran 1 1/4" line as well as over sized the actual drop from the street because the pressure here is stupid low. 1.1" of H2O on the coldest day of the year. They did something on their end to boost things a bit but would still only guarantee 4" H2O. So I had a 10" H2O gauge installed so I can keep an eye on things over the winter. Turn gas on, turn valve to gauge and the SOB goes right past 10" and nearly back to the 0". Guy grabs a digital meter off the truck and reads 12.6". Utility says not possible so I buy a 2nd gauge that goes to 15" and pop that on tonight, 11". Utility is having an engineer come tomorrow to see it first hand.

So to summarize, every guy from the emergency response team that showed up said exactly what you did about the piping. Made me very glad I paid someone to do it
 
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Old 12-13-11, 05:23 PM
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Having excitement like that, I can do without.
Good for the supervisor. There are still a few of us out there who take pride it our work.
Keep us up to speed on the saga of the gas pressure.
 
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Old 12-13-11, 05:24 PM
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A quick question for the pros and more experienced than I. The existing heating loop has one of those air purgers with the expansion tank mounted to the bottom. Does the tank have to be there or can it be anywhere in the near boiler piping? It's a bit hard to see from those pics but the rest of the heating stuff is going on that far wall and there is not much room. I may need to put that tank off to the side or something a bit crazy to make it all fit nicely.

Still haven't pulled the trigger on the manifold and accessories that are planned yet. Frankly I'm beat up at this point and may just hook to the existing loop that I haven't cut out yet. At least we'll have some heat while I mount the plywood and get the rest of the stuff sorted out. Might be better at this point to make the switch closer to spring. Still in the heating season so we can see how things are working but past the potentially dangerous temps.
 
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Old 12-13-11, 05:30 PM
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The boiler feed & expansion tank should go on the supply side of the boiler with the circulator a short distance downstream of them. That should be covered in the install manual.
 
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Old 12-13-11, 05:41 PM
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Originally Posted by Grady View Post
The boiler feed & expansion tank should go on the supply side of the boiler with the circulator a short distance downstream of them. That should be covered in the install manual.
OK. Actually the manual is pretty weak. I believe the Elite manual goes more in depth on the heating side of things. I'll check in there. You can see the old system in the one picture. That's basically what I'm either moving or connecting too. I'm sure I'll come up with some way to pipe it that works cleanly and still leaves access to everything.

Don't they have a magic expansion tank yet that is about the size of a beer can?
 
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Old 12-13-11, 05:45 PM
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If you find one of those magic expansion tanks, let me know & I'll buy a truckload.
 
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Old 12-15-11, 07:20 AM
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I went through the old aqua-stat thread last night. I'ts not apples to apples but the only setting I can find in the vision control is burner offset. It's defaulted to 5 with a max of 18. Seems that it's not really a differential, just a straight offset for the target temp. I'll have to call HTP to confirm.

Was also reading a nice little white paper B&G put together on zoning. From reading that I'm beginning to understand just how screwed up the existing single zone loop is. both ends of the 1" loop are restricted with runs of 1/2", baseboard at one end and a very badly plumbed convector at the other. I'll have to do a temp connection just to get something going. But it seems I'm going to have to get serious about my zoning options and get it in place sooner rather than later.

The rough plan was to use a Rifeng radiant manifold, matching zone valves and an Alpha pump. Just run each old convector off the manifold for now with the intention of transitioning to radiant soon. On paper I like the versatility that I'm given with that plan but B&G seems to be advocating one circ per zone, as opposed to one variable pump for the whole system as I'm thinking.
 
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Old 12-20-11, 01:11 PM
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Well the heat is on. got it tied in on Sunday. So far so good. Definitely a few details to address but overall we are happy. I just tied in to the old loops for now. I have one convector that has no air at the bleeder but there's clearly an air block somewhere. Can't quite get it hot. Also the circulator noise is slightly annoying. I'm sure it's been there all along but you couldn't hear it over the sound of the oil boiler before!
 
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Old 12-20-11, 07:26 PM
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That paper was likely written many moons before variable speed pumps.
 
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Old 12-21-11, 05:03 AM
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Originally Posted by Grady View Post
That paper was likely written many moons before variable speed pumps.
Very good point. I'll have to take it up again in January. I think overall the comfort is vastly improved running lower temps for a longer burn. But that makes the circulator noise that much more annoying.

I do like the manifold with a variable speed pump but we don't know for sure if the whole house will be radiant or just the 1st floor. Seeing as that would almost certainly mean two different temps, or more, I can see having to toss whatever manifold we buy now out and split it into two down the road for the different areas. Maybe I should just start with two now, split the floors now and hope it all works down the road.

Thanks keeping tabs on this thread. I know I've kind of turned it into a blog rather than a thread with a specific question. But I also don't want to clog the forum with every little update as a separate thread either.
 
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Old 06-22-12, 09:59 AM
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How noisy is your unit?

Hi,
I am planning on installing Versa-Hydro in my house (converting from electric: one hydronic heating zone + one hydro-air zone and dhw) - another option would be to go with HE boiler+indirect water tank (after rebated Versa probably will be $500 more expensive). The most appealing thing for me about versa is its size - I have a very limited space. Unfortunately while doing research could not find a lot of reviews of versa - I guess it's kind of new and a bit unusual product. After heaving it for 6 month are you happy with it? Any problem? Any disadvantage you might think comparing to boiler+storage tank setup?
And the one question I could not find answer - how loud is the unit? It will be installed in a utility room next to my family room (I have a split entry house) with just a regular wall in between.
Will appreciate any info/suggestion.
 
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Old 06-22-12, 05:52 PM
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It makes some noise. When the blower is fully spooled up it sounds like a quiet fan, which is what it is. The pumps make a bit of noise too. The heat exchanger pump makes a bit of a squeaking noise when it's dialed all the way down to 10%. As these things go though it's about as quiet as you can get. We basically never hear it running unless I happen to be in the basement when it spools up to full speed, which is not often. Oddly what I did hear that I never did before was the circulator pump noise being transmitted through the house via the heating pipes.

I would say overall the Versa is cheaper than the Elite when taking into account the amount of near boiler piping of the Elite and the finicky nature of the Elite heat exchanger. I'm certainly VERY glad I went with the Versa Hyrdro over the Versa Flame or Elite.

My complaints are that the outdoor temp sensor is way off, HTP doesn't care and they should as the entire boiler is based off that outdoor reading.

Also I think DHW mode could be much improved. Any call for water and it will turn on even though there is plenty of storage capacity. I'd also like to see them use the heat exchanger pump to circulate the water in the tank even when in DHW mode only, thereby avoiding this constant temp lockout mode and reducing the cycling. Really they could use a better firmware for this side of it.

Having said all that we LOVE this thing. Quiet operation, endless high pressure hot water that never varies and an incredibly comfortable house in the winter with no other changes. The lower temps with a longer burn time just made the house so nice and comfortable. We were able to leave the set point down a couple degrees and still be more comfortable than in years past. While I do have a couple little nitpick things about it, I would not give it up for the world.

We have saved a HUGE amount on our fuel bills over oil, but when compared to my neighbors gas bill with an old system it's not really that much better. As many have said, once these things get into the real world the efficiency is often irrelevant. Hopefully things will improve as time and money allow us to properly insulate the house and switch to radiant floor heat.
 
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Old 06-23-12, 08:07 PM
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Thanks a lot for the info!
 
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