Hot Water Boiler piping


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Old 09-20-06, 05:33 PM
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Question Hot Water Boiler piping

I have recently purchased a burnham205 hot water boiler to replace a 25 year old boiler. I need to know if I should use copper or Black for piping. Also I am not sure where the city water feed should go. As per existing piping, the water feed is connected to the return. However, Burnham installation manual shows the water piping diagram and the water feed is connected to the supply through diaphragm fittings.

Thanks for any help in advance
 
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Old 09-20-06, 06:13 PM
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Either copper or black iron should be fine. You could also do both, making the switch ideally across a brass or bronze fitting (like a zone valve, ball valve, circulator flange, etc.).

Figure 3 in the installation manual (I have a Burnham 206) is how you should pipe this boiler. When in doubt, follow the directions.

Note that if you put the circulator in the "alternate location", then you should also locate the expansion/diaphragm tank connection there also. It would be cut in just before the shut-off valve. But your system will be happier if you follow Figure 3 to the letter.

You don't necessarily need the by-pass or the balancing valve, however. Depends on the specifics of your system.
 
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Old 09-21-06, 05:58 AM
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Let me know if what I am thinking is not correct.

Based on figure 3 in the installation manual, when the city water(cold) enters the supply(Hot) when needed, it will mix with the supply hot water and bring down the temperature. Than travels through the baseboards and come back to the boiler through the return to be heated again.
Isn't this inefficient when compared to feeding the city water to the return than enter the boiler to be heated before it is supplied to the baseboards ?.

xiphias, if you donít mind me asking: you mentioned you have the Burnham 206. What is the SF of the house, how old and how well insulated? I just wanted to compair with what I have

Thanks in advance
 
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Old 09-21-06, 06:45 AM
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The city water only really enters once, when you fill the system. Then it should basically never add water except when you drain the system for maintenance or whatever. If you had a leak somewhere, then the autofill would slowly add make-up water (although this is a thing to be avoided). Keep in mind that adding fresh, oxygen-rich water to a closed loop heating system is about the worst thing you can do to it. You want to fill it up and be done. More or less.

Think of the pressure reducer/auto-fill as 1) a means to reduce the pressure from city to heating system, and 2) a convenience for maintenance, and a bit of an insurance policy if you do develop an undetected leak somewhere. Otherwise, the system could drain out and your boiler would fire with little to no water in the system, unless you have a low-water cutoff installed. Not good.

The reason the installation manual shows the water connection at the expansion tank, just upstream from the circulator, is because from a pressure perspective, that is the most "pressure change neutral" location in the system. So the normal fluctuations of system pressure (a few psi between when the system is cold and when it is hot) will not cause water to auto-feed.

I have a 206 which is actually going bye bye in a couple weeks for a variety of reasons. Long story. Heating load-wise, which is what you're asking, it is unfortunately more than double oversized for the house (2100 sf; 2 zones plus an indirect; design day heat loss about 50k BTU/hr; 64k BTU/hr baseboard output).

I hope you did a heat loss calculation to size your boiler. What kind of specs on your house?
 
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Old 09-21-06, 08:10 AM
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Thanks xiphias
How do I find out if autofill is adding water due to a leak. Also what is better have a auto feed or manual feed. I have a watts 1560(not sure if it is a auto fill or manual). Which will be replaced with the new boiler. Any recommendation?

The heat loss calculation came out to be 86K btu and the house is about 1800sf , 160 feet basebord, 50 year old, 3Ē insulation on attic(will be adding more soon), not well insulated walls. Is 205 oversized?

Thanks in advance
 
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Old 09-21-06, 09:10 AM
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You are probably sized about right.

The IBR of a 205 is 94k BTU/hr. Just right for 86k loss. The 204 is IBR 70k BTU/hr so it's too small.

Another way to size is use your 160 ft of baseboard heating element. So 160 ft at ~550 BTU/hr output per foot, assuming standard copper fin-tube baseboard with a supply temp of 180F. 160 * 550 = 88k BTU/hr output, or just about perfect for your 86k heat loss.

Say adding insulation to the attic takes you from 86k loss to 76k loss. (You could play with insulation scenarios in a heat loss package like slantfin's freebie). You're still sized about right.

In an ideal world, the sequence of operation is:

1) tighten and insulate the building envelope
2) do the heat loss calc
3) size the boiler and the radiation to the heat loss

But in the real world that often doesn't happen, which makes checking the possible output of the installed radiation against the heat loss and the boiler size a useful exercise. So even if you didn't improve the building envelope, your boiler is still capable of delivering rated capacity to the heating elements.

In any event, it sounds like you've got an appropriate boiler for the job. Good luck on the install. Post some pics when you're done!

Grady or other knowledgeable sort will have to weigh in on the various PRV options.

To check for system leak, close the ball valve that should be upstream from the fill valve and backflow preventer. Watch the system pressure over several days. If it drops more than the normal few psi fluctation between system cold and system hot, then you've got a leak somewhere.
 

Last edited by xiphias; 09-21-06 at 09:30 AM.
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Old 09-21-06, 05:51 PM
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Reducing valve

All I ever use is the B&G FB-38. The reason? Everybody around here carries them. Of every 500 boilers I see, one or two might have something else. I have no problem with the others, just don't see them. On a new installation, I prefer to use a low water cut-off & after the initial fill & purge, shut off the "feed" valve. The only exception to this would be if the homeowner goes away for a period of time. Even then, a low temperature alarm of some sort is preferable, in my opinion, than leaving the reducing valve turned on.
 
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Old 09-22-06, 09:01 AM
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Thanks everyone for the help
 
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Old 09-25-06, 08:13 AM
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Can someone help me to understand the difference between Air Purger combination with the Hydronic Vent VS Junior Spirovent and what is recommended?

Thanks in advance
 
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Old 09-25-06, 09:52 AM
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Not sure if I understand the question.

Looking at the ever-reliable Figure 3 in the Series2 install manual, the "air vent" and "air eliminator" could be a Spirovent Junior. It has a tapping below to hang the expansion tank and you can cut in the water supply stuff there as well. Nice to have a valve there, too, just above the tank, to facilitate future replacement.

Instead of a Spirovent, you could also use a Taco air scoop

http://www.taco-hvac.com/uploads/FileLibrary/100-7.2_AirScoopSht.pdf

and stick a HyVent in the top. I think the Amtrol "air purger" is basically the same setup.

Some like one, some like the other, some like yet another. Those are the two that I know about. The Taco, I believe, requires an 18" straight run of pipe on the inlet to allow the flow to stabilize before entering the scoop. The Spirovent does not. The spirovent probably costs more. Maybe not.

And now I need to get the salsa off my shirt.... Doh!
 
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Old 09-29-06, 06:23 AM
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Thanks xiphias. Spirovent do cost more, about 3 times more. I checked the price other day. What I am hearing from the guys around here is that spirovent is much more efficient and effective than the others. Does anyone else think differently?
 
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Old 09-29-06, 07:06 AM
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I presently have a spirovent. It seems to work just fine. From dozen or so heating guys I've talked to, there is exactly a 50-50 split on spirovent vs. the traditional air scoop with vent.

Probably a Ford or Chevy kinda thing. Having no experience with the traditional air scoop, I would say let your piping layout inform the decision on which to use. Got room for the 18" approach piping? Go with traditional, it's cheaper. Cramped? Go with spirovent.

That said, the spirovent could also benefit from whatever straight approach length you can give it.
 
 

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