New boiler & water heater for single pipe steam system... recommendations?

HeronHouse

We have a 3.5 story townhouse from 1889 in NYC. Heating system is single pipe steam from an ancient oil-fired boiler with a coil for hot water. The heat is not bad but the hot water is not working well and the oil bills are killing us. So our plumber is looking at a gas conversion, installation of new boiler, and an indirect water heater (his recommendation).
My questions are: is the indirect water heater a good way to go, even with a steam boiler? I'd say the boiler gets used for heat about 4-5 months of the year here. Will it be economical?
And I would love recommendations/warnings about brands of gas steam boilers and indirect water heaters. I do trust our plumber but I'd love to get some other opinions. He's great but not a hardcore steamhead like the folks on here!
Thanks much
HH

newagedawn

if electricity in the city is not bad consider going with an electric water heater, my opinion on converting to gas is do it and the near boiler piping is very important for a 1 pipie , check on the find a contractor here for a true steam pro as most plumbers are not familiar with steam

nicholas bonham-carter

One of the most important skills needed for a good steam installer is being able and willing to read and follow the instructions in the installation manual. There is no room for any one from the “i’ve been doing it this way for 30 years.” school.
The radiator heat values, (EDR), must be added up for their total value, of square feet of steam, in order to size the boiler.
Count on replacing the main, (not radiator vents), at the same time, as the old ones are probably to blame for your high fuel bills.
Pictures of the present setup posted here would be useful in getting advice.—NBC

JUGHNE

IIWM, I would go for the gas steam boiler and a separate gas water heater.
The efficiency for an indirect heater connected to a steam boiler might be close to just a separate hot water heater.....no pump ...simple controls....no hot boiler in the summer warming the basement....less expensive replacement in the future.

You might consider a good look at the chimney liner.

Pictures posted would get you some good advice here.

lchmb

could look at a Rinnai continuum. Put a recirc loop on it..just make sure it's sized properly for the hw load..

newagedawn

good gas water heater is way better than an electric one

HeronHouse

Thanks for the great info so far. I'm attaching some pictures of the current beast and its nearby plumbing.

We are not considering anything electric... our electrical system in our home doesn't have the capacity anyway.

I'm not hearing a great love of the indirect water heaters from you all. Obviously they cost more up front. Practically free hot water in the Winter, when the boiler is running anyway, but I wonder how it shakes out for the rest of the year. Does a steam boiler have the ability to modulate so it's reasonably efficient in just heating domestic water in the warmer months? Obviously I hope we're not boiling a bunch of water above 212 just so that I can take a 105-degree shower.

One of the reasons we are thinking of going with an indirect water heater is the limited space in the chimney for venting.

The current venting in the chimney is shown in the picture. We will definitely take a look at the chimney liner.

NBC, can you tell me what you meant by "replacing the main"?
NewAgeDawn, are you talking about the same thing when you say to look at the near boiler piping?

Thanks again for sharing your expertise, all.
-HH

BobC

Indirects are great if you use a lot of hot water but if your hot water needs are modest you can't beat a gas fired hot water tank. My gas usage in the summer is 6 or 7 therms (that is for the gas stove and the gas hot water heater).

They can use a y adapter to feed both the gas boiler and gas hot water heater into your chimney. The chimney will have to be lined.

nicholas bonham-carter

The main venting will probably need to be replaced.
These vents let the air out so the steam can enter the the pipes, and radiators. The radiator vents are not able to do that job without burning a lot of extra fuel, which may be the reason for your high oil consumption.
Order a copy of the steam books from the bookstore here, and you will become more informed than many plumbers.—NBC

Jamie Hall

On indirects and hot water and so on with a steam boiler. First, in a sense the boiler can -- and should -- modulate down when the only demand is for hot water. There is a gadget called an aquastat which will maintain the boiler at the temperature required by the indirect, if there hasn't been a recent call for steam. Such as in the summer. However, a gas water heater wouldn't take up any more space in the basement, and has a real advantage in much faster recovery (usually!) which is nice to have all year. I'd go that route.

The "near boiler piping" refers to the piping immediately connected to the boiler -- the riser or risers, header, and equalizer, and the way connections are made to the rest of the system. Each boiler design has minimum requirements for the way that is to be done, and it is important to adhere to those -- or go beyond them. It's unlikely that your present near boiler piping would be suitable (if for no other reason than the header -- that horizontal pipe which is fed at one end by the riser, then has the takeoffs to the building, then drops as the equalizer) is a little low for best results just as it stands.

Main venting refers to the big vents located at the ends of the steam mains. It's purpose is to allow steam to rapidly fill the mains, thus getting steam more nearly simultaneously to all the radiators. Don't skimp on it. Vents are cheap...

JUGHNE

How does the condensate water return to the boiler?
Pictures of the right hand side of the boiler would be good to look at.
Are there return pipes on the floor or coming out of the floor?
This may be an important consideration for piping your new boiler.

Noel

I'm a licensed gas tech and work for a boiler and water heater manufacturer, and have since 2001 (not all the same manufacturer). I have a steam boiler in my house with an indirect water heater connected to it. It runs on a timer (with an override switch in a closet) for less than 2 hours each morning. We rarely need to reheat it during the day, but a twist of the override timer switch in the closet brings it on instantly. An aquastat on the boiler keeps it from making steam temperatures. I've considered putting a circulator post-purge timer on it to cool the boiler back down after it runs, but I don't think it would pay for itself. I have fast, inexpensive DHW in a small space. I can recommend an indirect water heater, correctly installed, in your situation.

HeronHouse

Thanks for all the great info.

JUGHNE said:

How does the condensate water return to the boiler?
Pictures of the right hand side of the boiler would be good to look at.
Are there return pipes on the floor or coming out of the floor?
This may be an important consideration for piping your new boiler.

I'm attaching a picture below that should show the condensate lines etc. If there's any improvements that will need to be made there I'd love to hear about them.

nicholas bonham-carter said:

The main venting will probably need to be replaced...
Order a copy of the steam books from the bookstore here, and you will become more informed than many plumbers.—NBC

Thank you Nicholas. My fiancée got me "The Lost Art" for a valentines gift ... now that's romantic! Now I just need to find the time to dig into it. You are helping me know what to look at.

BobC said:

Indirects are great if you use a lot of hot water but if your hot water needs are modest you can't beat a gas fired hot water tank.

Thanks Bob, we have 2 units and 6-7 people total in the building, plus a dishwasher and laundry incoming. So there's a fair bit of hot water demand.

BobC said:

They can use a y adapter to feed both the gas boiler and gas hot water heater into your chimney. The chimney will have to be lined.

A couple of plumbers who looked at it seemed to think that here in NYC the chimney is not going to be considered adequate for both boiler and separate hot water heater. Don't know if it's capacity, or that they shouldn't share for other reasons. Could be a regional code variation perhaps?

Jamie Hall said:

... a gas water heater wouldn't take up any more space in the basement, and has a real advantage in much faster recovery (usually!) which is nice to have all year.

I'd heard that the indirect will actually have a faster recovery? Figured it was because of the amount of muscle it's got behind it.

Anyway Jamie, thanks for clarifying about the near boiler piping and main vents. Not sure if this plumber knows about this stuff so I'll make sure that's all part of the project.

Noel said:

I'm a licensed gas tech and work for a boiler and water heater manufacturer, and have since 2001 (not all the same manufacturer). I have a steam boiler in my house with an indirect water heater connected to it. It runs on a timer (with an override switch in a closet) for less than 2 hours each morning. We rarely need to reheat it during the day, but a twist of the override timer switch in the closet brings it on instantly. An aquastat on the boiler keeps it from making steam temperatures. I've considered putting a circulator post-purge timer on it to cool the boiler back down after it runs, but I don't think it would pay for itself. I have fast, inexpensive DHW in a small space. I can recommend an indirect water heater, correctly installed, in your situation.

Thanks so much for the specific info, sounds much like our situation. Can you tell me the brand of boiler and indirect you have?

Thanks so much, you all are very kind to share your knowledge.
HH

Noel

Brand isn't all that important, a good installer is. Mine is a Peerless oil boiler and a 40 gallon stainless steel indirect. I have a well for water so there is no chlorine to be a problem with the stainless steel. Use the equipment that your installer prefers, as he will have a good supply chain to work with. Be sure he does service and wants to be your contractor for the long term. He is what makes the job work.

JohnNY

My company installs steam boilers and indirects in Manhattan and Brooklyn on the regular. Electric hot water is not practical in this city and it is extremely difficult to vent tankless or instantaneous water heaters within NYC limits.

HVACNUT

Like the near boiler piping, the manufacturer should have a diagram in the I&O how they want an indirect piped. And even if it's not in the manual, install a WYE strainer before the circulator and HX.

HeronHouse

Ok! Thanks to this info and my readings in The Lost Art of Steam Heating, I looked around and my mains do NOT have vents at all! So we'll be adding those but other than that (big) oversight, the system seems to be piped according to the book.

I'd love to ask another question of you helpful folks: I added up the EDR of the radiators, as instructed in the book, and got between 272 - 292 (this variance depending on a couple of radiator swaps that we might do). Looking at the New Yorker boilers, the GCS40C is rated for 263 sq. ft. and the GCS50C is rated for 354 sq. ft. That's quite a big gap. Which one to go with? I'm assuming the larger one, to be sure we aren't undersized at all. But my plumber thinks we'll be fine with the smaller one. Thoughts?

-HH

Jamie Hall

There is a 33% pickup factor built into those ratings. Often not all of that is needed. If you insulate all your steam mains and possibly the risers really well, if you can get at them, and have really good main venting (don't cheat!) you may be OK with the smaller unit -- particularly if you go on the lower end of your EDR range.