Can undersized system cause excessive makeup water?

slapp

I have an undersized boiler, resulted from previous owner adding on rooms to the house and not increasing the size of the boiler. This is my second season in the house and again I am using excessive amounts of make up water. I need to fill it almost every day. The amount of water I am losing would have to show itself at the vents and connections. Everything looks good. I haven't checked for a cracked boiler, something to do during the spring I guess from the directions I see here.

My question is, since the boiler is undersized, I have about 5 radiators that only heat half way. The ends with the vents are cool to the touch, but maybe a few feet down, you can't touch it. Could those open vents, some how be letting enough wet air out that it is causing my excessive make up? Or am I most likely looking at a cracked boiler?

NOTE: that I am slowly taking rooms off the steam system and using other means to heat them to bring the system back into balance.

BobC

If your losing water it has to be going somewhere, if it is undersized that would not cause water loss. If any boiler returns are buried that could be where the leak is. On a cold day check the chimney for large plumes of steam, that would indicate a leak into the firebox.

Do you know what the EDR of your boiler is and how that compares to the EDR of all the radiators? Arre all the pipes in the basement insulated?

What kind of main vents do you have and what kind of vents are on the radiators?

Bob

nicholas bonham-carter

Is this a one-pipe, or two pipe system? Have you calculated the EDR of your radiators, and compared that to the boiler rating plate.
You can easily check for a cracked boiler, now that the winter has become mild.
Let the boiler cool, and then overfill it up to the header, which will become cold with the fresh water. Let the boiler sit for a few hours, and then look into the fire box for any leaks which should become readily apparent, if they are there.
Losing enough water to show up in 24 hours would be more than a few leaky vents.--NBC

Steamhead

slapp said:

NOTE: that I am slowly taking rooms off the steam system and using other means to heat them to bring the system back into balance.

If you have a leaking boiler, just get a big enough replacement so it can heat the entire house.

ChrisJ

An undersized boiler would use less water if anything because the steam never hits the vents, except for main vents.

You'll still loose some through the radiators due to moist air leaving, but it'd be less than a properly sized boiler and far less than oversized. No matter what steam escapes through the vents if it's at the end of the radiator because they take time to close, and often open and shut immediately even with steam right near them.


Sounds like you have a leaking block, or serious leak somewhere in the system. With an undersized boiler I highly doubt you're losing that much due to leaking packing nuts etc.

slapp

Sorry, should have included the details in the initial post.

Boiler is an Burnham Independence I5. Spec for it says 358. I, with the help of a plumber friend calculated the house at 470! Single Pipe. The Main has 2 Gorton #2's. Steam gets from the header to the main vents in about 8 minutes. The radiator vents are Heat-Timer Varivalve. All the basement pipes are insulated, half the main goes through a crawl space, those are all insulated as well. There are no buried returns, I went to every tap off the main and couldn't see/hear anything.

I will check check the chimney as well as do the fill test when I get a mild day. (Wednesday)

@Steamhead Two reasons for not wanting to get a larger boiler right now, wife wants some heated floors in a few rooms and the next size up would really require a new gas meter to service the whole system properly. So I am trying to hold off and see if I can remove some load.

Fred

The boiler is too small to effectively heat that much radiation but that is a seperate issue from the water loss. There is a leak somewhere, most likely in the boiler block, as has been suggested.

ChrisJ

Fred said:

The boiler is too small to effectively heat that much radiation but that is a seperate issue from the water loss. There is a leak somewhere, most likely in the boiler block, as has been suggested.

Actually,
At 115,000 btu output that boiler in theory could drive 479sqft of radiation, including piping losses.

With 470sqft connected, assuming all of the piping was very well insulated and the radiators are vented slow (get rid of the heat timer vents!!!) it could work.

That said, I've got a feeling that boiler is what's leaking.

Fred

ChrisJ said:

Fred said:

The boiler is too small to effectively heat that much radiation but that is a seperate issue from the water loss. There is a leak somewhere, most likely in the boiler block, as has been suggested.

Actually,
At 115,000 btu output that boiler in theory could drive 479sqft of radiation, including piping losses.

With 470sqft connected, assuming all of the piping was very well insulated and the radiators are vented slow (get rid of the heat timer vents!!!) it could work.
That said, I've got a feeling that boiler is what's leaking.

With 112,800 BTU of radiation, that only leaves him a little less than 10 sq. ft. for his header, mains and run-outs. That's 2% above his EDR. I don't think so.

slapp

@ChrisJ are saying that the 358 on the spec sheet doesn't include pipe loss, so in theory it can output a certain percentage more that is just undocumented? My 470 number is radiators only...so I am sure that I need to add in more for piping. I have a 110 foot main.

ChrisJ

Fred said:

ChrisJ said:

Fred said:

The boiler is too small to effectively heat that much radiation but that is a seperate issue from the water loss. There is a leak somewhere, most likely in the boiler block, as has been suggested.

Actually,
At 115,000 btu output that boiler in theory could drive 479sqft of radiation, including piping losses.

With 470sqft connected, assuming all of the piping was very well insulated and the radiators are vented slow (get rid of the heat timer vents!!!) it could work.
That said, I've got a feeling that boiler is what's leaking.

With 112,800 BTU of radiation, that only leaves him a little less than 10 sq. ft. for his header, mains and run-outs. That's 2% above his EDR. I don't think so.

Irreverent unless you know his building's heatloss.

98% chance the system could be balanced and as long as it heats the home (and being most steam systems are grossly oversized.....) it'd be fine.


Prove me wrong.
I already used my system to prove my point, your move.

ChrisJ

slapp said:

@ChrisJ are saying that the 358 on the spec sheet doesn't include pipe loss, so in theory it can output a certain percentage more that is just undocumented?

Correct.
That 358sqft is assuming a 33% loss in piping which is ridiculous.
You'll find this is argued quite a bit on the forum. Most guys use the 33% figure, a few of us recommend smaller. I've felt 10-20% is a good number.

One of our members who does this for a living has even used boilers that are smaller than necessary to drive the connected radiation with success.

Point being, for now I'd ignore the size of the boiler and try to find the leak. We'll cross the boiler size bridge when we come to it.

Fred

I already used my system to prove my point, your move.
Your system runs with 2% overhead? I'm not trying to prove you wrong, I'm just stating that "I don't think so" . No different than you stating "You think so". We're all here to help. The OP has what he has, neither of us can change that. He has already said he is shutting rads down to heat a portion of his house and he is losing water to boot.

ChrisJ

Fred said:

I already used my system to prove my point, your move.
Your system runs with 2% overhead? I'm not trying to prove you wrong, I'm just stating that "I don't think so" . No different than you stating "You think so". We're all here to help. The OP has what he has, neither of us can change that. He has already said he is shutting rads down to heat a portion of his house and he is losing water to boot.

He's shutting down radiators because he's using heat-timer varivalves.

Losing water is a separate issue as already stated above.

slapp

Right, really it is my move now to test the boiler...will report back, thanks for all the insight.

Fred

ChrisJ said:

Fred said:

I already used my system to prove my point, your move.
Your system runs with 2% overhead? I'm not trying to prove you wrong, I'm just stating that "I don't think so" . No different than you stating "You think so". We're all here to help. The OP has what he has, neither of us can change that. He has already said he is shutting rads down to heat a portion of his house and he is losing water to boot.

He's shutting down radiators because he's using heat-timer varivalves.
Losing water is a separate issue as already stated above.

Point 1, is an unknown when there are several factors in play. It could be the varivents, it could be the boiler size, it could be steam loss through a cracked boiler, going up the chimney, or it could be a combination of those things. None of us can isolate the real cause, at this point.
You didn't answer the question as to if you are running your system a 2% overhead. I'm seriously interested in that.

ChrisJ

No, I'm running 10%.
The Steam Whisperer has done below 0%.

It's all in the venting.

Fred

ChrisJ said:

No, I'm running 10%.
The Steam Whisperer has done below 0%.

It's all in the venting.

Thanks, 10% is great! It's all in the venting? I'm not understanding how you control heat loss on headers, mains and run-outs with venting. Please explain. Steam Wisperer has done that on a one pipe system ? Under what circumstances?

ChrisJ

Fred said:

ChrisJ said:

No, I'm running 10%.
The Steam Whisperer has done below 0%.

It's all in the venting.

Thanks, 10% is great! It's all in the venting? I'm not understanding how you control heat loss on headers, mains and run-outs with venting. Please explain. Steam Wisperer has done that on a one pipe system ? Under what circumstances?

I'm only posting this because I feel it may help the OP feel more confident assuming he can easily fix the leak.


https://heatinghelp.com/systems-help-center/taking-another-look-at-steam-boiler-sizing-methods/

Fred

@ChrisJ , great article! His approach makes a lot more sense to me. Pick a boiler, based on conventional full radiation + piping and Pick-up and then use an adjustable burner to build capacity up too a working, balanced system. That makes a lot more sense to me than buying a much smaller boiler than the conventional approach and hope it meets the need. His approach says you have the ability to get back to "conventional" if need be. You can go down but you can't go up, if you pick a boiler that is too small. A two stage gas valve will get you part way there but a fully adjustable burner would be great.

"A good starting point is probably using a boiler that can be fired to the conventional full radiation + piping and pick up load and then using an adjustable input burner. For natural gas I have been using the Slant Fin Intrepid series with either a HeatWise gas burner or PowerFlame X4M burner if I want modulated input"

ChrisJ

A two stage gas valve gets you no where other than a ton of excess air and reduced combustion efficiency. The only time it makes sense is when an oversized boiler is already in place and needs to be tamed.

Fred

If one follows his venting suggestions, I would think it might allow you to run on low fire a good portion of the time, no?

slapp

Thanks for the article, read through it twice and probably need to do 2 more times. Starting to realize that the fast venting that the heat timer valves are doing, isn't necessarily right for every room and it certainly isn't helping with the rooms I need to heat up faster because in the grand scheme, they all are fast.

It also gave me an appreciation that "a steam boiler running very long, steady and efficient firing cycles, with short off times that greatly cut standby losses and provide incredibly stable heating to the home."

JUGHNE

The rads that do not heat all the way across, do they still furnish enough heat for their rooms on your typical coldest day? (near design temp day)

BobC

One test to find a leak in a boiler is to fill it up till the water is up in the boiler risers for a few hours and look around for boiler leaks. Do this when the boiler is warm or cold and don't forget to drain it back down to the normal level when your done.

Once you find and fix the leak think about venting the rads slowly. Maid O Mist has a 5L vent kit that comes with 5 different size orifices.

http://www.amazon.com/Maid-Steam-Angle-Radiator-Valve/dp/B003DV3AGE/ref=sr_1_2?ie=UTF8&qid=1457392463&sr=8-2&keywords=maid+o+mist+5L

These make balancing a system easier.

Bob

The Steam Whisperer

For balancing a marginal or undersized boiler, anything bigger than the #5 MoM is too big, IMO. I do a 6 if the boiler is oversized, like most, and can't be downfired. My favorite is the Ventrite or Tunstall. It adjusts roughly between the 4 and the 5. It is about the slowest adjustable vent that Gerry Gill tested. MoM is out of Chi-town and the Ventrite/Tunstall is out of Michigan.

slapp

@JUGHNE No, on the coldest days, the boiler runs full duty cycle and if outside is between 10-20F then I can keep 60 degrees, on the coldest days 0-10F I can keep about 57. I know that there are rooms in my house that have tremendous heat loss. For those days I turn off the radiator and close the doors so that the rest of the house can stay up.

slapp

Well that answers that. The water was pouring out...

BobC

That usually means it's time for a new boiler, have someone find where the hole is and then start getting quotes for a new boiler (assuming it's a hole in the block and not from a connection to the block).

Make sure the boiler is sized correctly and as the installer for pictures of his previous installs so we can see what kind of work he does. All the steam pipes have to be threaded steel, not copper.

Bob

slapp

The install manual for the I5 clearly states to pipe the water feeder into the wet return. Instead mine is piped right by the pressure relief. I am sure the flow of cool water straight into the hot boiler helped the crack along.

Abracadabra

The installer must have read a different manual

ChrisJ

Looks like you need a new steamer.

The fact yours cannot heat the house means you need a bigger boiler without a doubt.

Please remember, the most important thing about a new boiler is who installs it.

KC_Jones

Also you could post some overall pictures of the current install and we can give you an idea if it has other issues and things to look for in the replacement. Where are you located? We may be able to recommend a good steam contractor in your area. You don't want just any contractor doing this, you want one that knows steam.

Fred

@slapp , it's a long shot but it doesn't hurt to try. How old is the boiler? There have been times when Burnham and especially other boiler manufacturers have given a credit for early block failure. Of course, if it's out of warranty and was improperly installed, it certainly at their descretion but it's worth a try. May get you a few hundred dollars towards a properly sized boiler. If you find a good installer, they may be willing to call Burnham Customer Service on your behalf and at least try. Sorry about this situation but at least you are towards the end of a heating season and have time to find a good installer.

slapp

Fred: I took off the exhaust housing to find it...hoping that it was just a loose plug (since the water was pouring out). The hole is right near the top, about 3 CM wide, 2 CM tall. It is on the end (of 5) of the cast iron pieces, ironically the farthest one from the poorly installed water feeder. I am definitely going to contact Burnham to see what they will do.




I am on Long Island, suffolk county.

Any chance that I can just replace the cast iron piece of this, everything else looks nice and new?

I have to say, after seeing some of the pictures of the headers that the teams here put together, I am ashamed of mine. Almost to the point where I don't want to post pictures of it. Ha!

Basically it is only using 1 of the 2 ports, and does a weird off pitch hookup to there the header dropped to what was an old Oil boiler. I have been in the house 1.5 years now and this work was done maybe 7 years from what I was able to gather from the previous owner.

But regardless, pictures of the header here, from when I was initially trying to find out what my problem was, first step was to see if I was getting any pressure at all. Clearly with that crack I wasn't able to.

Fred

If the boiler is otherwise fine, the end section could be replaced but you just don't know what the other sections are like. One or more of them could also be ready to go. Even the entire block could be replaced, but, given the boiler is undersized and you probably want to improve the header/piping, I'd be inclined to ask for some credit towards a new boiler. If you have the documents that came with the boiler, a seven year old boiler should have some warranty left on it. I'm just not sure if that warranty is transferrable to a new home owner. (I think it is But not sure). Might as well start over and get it done right this time.

slapp

Yeah, due to the steam, you can see that the other sections have more Rust/deposits than I would expect. I called Burnham US Boiler and they are going to get back in touch with me about what they can do.

Now my thoughts go back to the original problem about boiler sizing. I agree that I can "start over and get it done right" but If I can recoop function from a new boiler (same size) and a proper header. Then if my plan still stands to put radiant in 3 other rooms in the house (already in 1 of them). Then I can remove those from the EDR calc and maybe the same boiler would work. I know, lots of "if's" in there.

Best thing right now...get it done right.

Fred

You will want to match the sq. ft. of steam, rating on the boiler plate to the total EDR of the remaining radiators. If you have to get a new boiler, anyway, I'm not sure why you might still feel the need to put radiant in the other three rooms, except maybe for some personal preference. If it were me, I'd "right size" the new boiler, spend the money on getting the near boiler piping optimum, insulate those pipes and deal with maintenance of a single steam system.

slapp

yes, it is personal, kinda...my wife wants it in the three rooms...

Got a call back from US Boiler. The said that while I have a 10 Year warranty on the block, there is a super small print sections about corrosion, which the lady on the phone says, it "sound like". That isn't covered, but they are willing to send me a new base and block for $700. Other than that they are offering a good will $500 rebate towards a new full boiler.

Then I can choose to have the old block sent back and if they deem it defective and not corrosion they will credit me for parts.

Thanks for all the help on this subject...I definitely learned a lot about the system.

Fred

I'd opt for the "good will" rebate and get a new boiler. If it is in fact a "good will" rebate, I'd be surprised if they even want the old block back. Maybe just confirmation from a licensed installer that he did, in fact replace the old boiler and its serial #. Make sure your wife understands that you have this opportunity to upgrade that boiler and what the added cost will be to change out to a different system for those two rooms. It may be that she has been so disappointed in the steam, because it is undersized that she can't imagine how comfortable a properly sized and installed system can be. Best of luck in whatever decision you make!

ChrisJ

Wow
I'm surprised they're willing to do anything. A new block and side panels for $700 is a steal IMO.

The only issue being your IN5 can't heat the house enough, of course some insulating, tightening windows etc could very well fix that. You'd be amazed what some insulation on steam piping can do too as well as proper piping around the boiler.