Steam-to-hydronic conversion using existing piping?

AHBklyn

My husband and I are about to commit to a NYSERDA-funded energy efficiency project for our two-family 1912 townhouse in Brooklyn, which includes converting our steam-heat system to hydronic. We're having some "cold feet" feelings and so I am posting in hope of getting some feedback and advice before we proceed.

The motivation for this conversion: our current steam system is sluggish (radiator farthest from the boiler takes 40 minutes to get hot). We've added 1 Gorton #2 to each 4" steam main (one main serves 1FL, other serves 2FL) and replaced all radiator vents with Maid-o-Mist Ds (2FL) and Cs (1FL), but that hasn't helped. The original plans for our house at the Dept of Buildings suggest the house originally had 2 boilers, one connected to each main. The house now has one 150K BTU Pennco boiler, circa 1992, 85% efficiency (tested by our NYSERDA-approved energy auditor), with Frankenstein piping to the two mains. In addition, the risers for two radiators above the boiler room are piped directly from the header (not the mains) and these radiators tend to get wet steam, perhaps in part because the condensate has to go back through the risers to the header. Pressuretrol is turned down low, per the advice I've received on this site.

Because we can't seem to improve the current system, despite talking to a steam consultant and 4 different HVAC contractors, we've been exploring a steam-to-hydronic conversion. I've read the web page about that on Heating Help and it sounds like it's difficult to do with pre-1920 radiators and a 1-pipe system. But the NYSERDA contractor seems to think he can do it, using the existing radiators and piping, creating a return from each radiator using new flex tubing or pvc. My main concern/question about the feasibility of this project relates to our two 4" steam mains, each of which runs about 20'. Is it really feasible and acceptable to reuse those in a hydronic system? It's hard to imagine running water through those huge pipes, both of which seem 100+ years old. Also, the main return line to the boiler (running along the basement floor) is only 2" pipe, and time and again boilermen have told me that's too small--but perhaps that matters less with a hydronic system?

Any thoughts, tips, or advice? Any questions I should be asking the contractor? Many thanks in advance for any input you have to offer!

ChrisJ

I'm sorry, I'm a bit confused.
If you get @JohnNY or @Paul S in there I'm sure they can make the steam system work very well, with far less work than converting it to hot water.

Paul S_3

@AHBklyn You can give me a call at 718 662 0725.....i can get this running great for you....im working in Flatbush now.... Call if you'd like..... Thanks @ChrisJ .... as far as a steam to hydronic conversion....i strongly advise against it if you can get this system running great and efficient..... it will cost alot more ...... as far as reusing the steam piping i would not....hot water system runs at almost 20 times the pressure of a normal steam system....and leaks are likely...

AHBklyn

Yes, @JohnNY is wonderful, he consulted for us and gave us some great recommendations about what we could try to improve our steam system, including a recommendation for a new boiler. That is what we will do as a Plan B, if we decide against the conversion.

But we are exploring the conversion to hot water because it would offer the potential to add on the system, like installing baseboards in the finished basement and bathrooms (which are unheated right now). Basically, I wrote this post because I'm wondering if anyone has advice or experience with conversions, especially with two 4" steam mains (as we have) and old cast-iron one-pipe radiators. Perhaps I should have mentioned in my first post that the contractor proposed two options. The less expensive one uses the existing piping to feed the radiators, and he will install piping to take the water back to the boiler. The more expensive one would involve snaking tubing for both supply and return and the adaptation of our current radiators. I just don't know if one or either of these are feasible, having no experience with this process! Thanks so much.

ChrisJ

What did Johnny NY say regarding a conversion?
He saw your system in person and likely gave the best advice regarding what to do. If he feels the system is in bad enough shape and warrants a conversion it's likely true. However, I've got a feeling that's not what happened.

A steam system can be added to as well.

KC_Jones

First are you positive your rads can even be converted? "True steam" rads can not be converted. Second I doubt anyone that actually knows steam is going to recommend a conversion. There are plenty of potential risks involved and I am sure those in the know will chime in on this thread especially @Steamhead.

All the things you say you can get with a conversion can be had with steam, including hot water baseboard.

Fred

You certainly can add a hot water loop to a steam boiler to heat the basement. I'm guessing that the reason it takes 40 minutes for steam to get to the furthest radiators is you still don't have enough main venting on those 4" mains. There is a lot of air that must be pushed out of those mains and one Gorton #2 is not enough. Did Johnny suggest more venting? Personally, I'd be very leery of trying to convert a one pipe steam system to hot water. I'd spend my money making the steam system right and add a hot water loop to the basement if desired.

STEAM DOCTOR

1. Almost any steam system can be made to work properly at considerably lower cost than conversion to hot water. Might need better venting. Might need boiler repipe or boiler replacement. Don't let anyone tell you that it can't be done.
2. The radiators and piping are more then 100 years old . Steam typically runs at 2 pounds of pressure or less. Hot water can run at up to 20 pounds of pressure. Can the radiators and piping handle the extra pressure without leaking or flooding?! Only way to know for sure is go through extensive pressure testing.
3. Balancing. You can't just slap pipes on the radiators and expect the water to flow evenly to all of the radiators. There is a method to the madness of balancing. You may end up with the exact same problem that you started off with. Do you trust those doing the conversion? How much do they know about the science and methods of balancing hot water systems?

STEAM DOCTOR

There are many options for adding heating loops. You can add a loop to the steam boiler. You can install a new hot water boiler. You can add a heat exchanger

Jamie Hall

Excuse me -- but @JohnNY 's suggestions should be Plan A. With very very very rare exceptions, it is less expensive and more satisfactory to spend a little time and effort getting a steam system to work right than it is to try to convert.

However, I'm going to bet that John didn't look at it and say something like "sure, I can do that, no problem". More likely -- since he is an honest and reliable individual -- he said that he could probably make it work much better. Unlike a snake oil salesman, however, he might not have promised the moon. Don't let that mislead you.

As to adding heat to other spaces, not currently heated, as several have noted there are a number of options for doing that. The one selected should depend on a good analysis of what is wanted and a good design -- both of which John can do.

JohnNY

Hi AHBrooklyn,
I'm sorry to know you're still having problems with those few radiators, but I still believe that a steam-to-water conversion is like bird hunting with a hand grenade.
Also, you don't have 4" mains. Your mains are 2"-diameter piping. I also see in my notes that there were a number of small problems with the piping and venting that are robbing the energy from the steam and cooling it before it could warm the rooms. I can stop in during the week if you'd like to go over some of the piping again.

These pictures are from our report to you in January:




Thank you, Wallies, for the kind words. I appreciate your confidence in my judgement.

Steamhead

What JohnNY said.

AHBklyn

Thanks, @ChrisJ , @Paul S, @Steamhead, @STEAM DOCTOR, @JohnNY, @Jamie Hall, @KC_Jones, and @Fred for your comments -- you answered my basic question: in the collective wisdom of this community, it's not a good idea to convert a steam system to hydronic one.

I'll talk to the NYSERDA contractor to find out if he can integrate @JohnNY 's recommendations about piping and a replacement boiler, rather than doing this conversion.

Thanks again for your time and input.

New England SteamWorks

What they said.

Fixing your steam system with a steam pro: Straightforward.

Riping it out (which you will have to do for hotwater: Nightmare

Effect on the character of your home: Unimaginable.

Folks like to work with what they know. The folks you've been working with (outside of @JohnNY) know hotwater. That's their comfort zone. It shows.

Give a steam pro half the money you'll spend on a conversion and you'll have one of the greatest steam systems ever.

Henry

If it is a one pipe system forget about it. If it is a two pipe system, we have done a lot of them with energy savings of up to 40%. Early cast iron radiators were over sized. You can use a mod/con boiler. The 160F temperature is only for less than 100 hours of operation in the North. Where are you located? PM for factual information.

New England SteamWorks

Saving 40% on a bad steam system is easy. I do it all the time. No water needed.

ChrisJ

Henry said:

If it is a one pipe system forget about it. If it is a two pipe system, we have done a lot of them with energy savings of up to 40%. Early cast iron radiators were over sized. You can use a mod/con boiler. The 160F temperature is only for less than 100 hours of operation in the North. Where are you located? PM for factual information.

@Steamhead He's at it again.

New England SteamWorks

Hatterasguy said:

Sure, you love your steam system but realize it can never be all that efficient. And, saving 40% on a system that is a train wreck is not a comparison to a mod-con.

Henry is correct.

One would have to assume that money is no object. Which of course it always is.

So the question is, once one of us steam guys goes in and does his stuff (for considerably less $ than doing your stuff), how much are you going to save on top of that? The answer is that the payback will be "not in the owners lifetime".

New England SteamWorks

On the other hand if the exercise is: "Let's build two identical houses and we'll put steam in ours and you put mod/con in yours, -I'll give you that. But that is a hypothetical. Which is of no value whatsoever to the owner of a home with steam heat. And sense no one builds new homes with steam heat, it also isn't of value to anyone else either. Just words with no real world application.

And then you have the whole "destroying the character of the house thing" which, while some people might not care, -drives me crazy.

Steamhead

Here we go again. As usual, Henry and Hatterasguy do not say what condition the steam systems were in before they were perverted, errrr, converted. To put their claims in proper perspective, see this thread:

http://forum.heatinghelp.com/discussion/145002/actual-savings-over-steam-heating

Some of you guys might want to bookmark that thread, as I have.

ChrisJ

@Hatterasguy If you can build a system with a modcon that can save 10% over my system, including extra installation (cost of boiler over CI) and maintenance costs, I'd be amazed. I'd be impressed if you could squeeze 5% out over my system. The maintenance costs alone are going to hurt you.

40% isn't happening, period.


Yes, modcons are more efficient, no one here has debated that.

We're debating whether it's cost effective, like your tankless video...........

I'd rather dump the extra money in tightening up the envelope over a modcon any day and not just in my house, probably 90% of houses out there.

If I had a hot water system, I honestly cannot say I'd go with a modcon either, there's a good chance I'd go with cast iron.

Gordy

All this bantering is pointless. However steamers size their boilers to the EDR. Water based systems are sized to the heat loss. So any excess in EDR becomes an advantage. Especially when a mod/con is used.

So one could take an existing steam system that is at its peak operating efficiency, compare the EDR, and boiler size of the system to what if it were water based with a right size to heat loss boiler, and if the radiation were over sized for the actual heat loss of the structure.


Oh, and I do seem to have viewed a lot of steamers who would love to have a modulating steamer with some using two stage gas valve trains.....

ChrisJ

Gordy said:

All this bantering is pointless. However steamers size their boilers to the EDR. Water based systems are sized to the heat loss. So any excess in EDR becomes an advantage. Especially when a mod/con is used.

So one could take an existing steam system that is at its peak operating efficiency, compare the EDR, and boiler size of the system to what if it were water based with a right size to heat loss boiler, and if the radiation were over sized for the actual heat loss of the structure.


Oh, and I do seem to have viewed a lot of steamers who would love to have a modulating steamer with some using two stage gas valve trains.....

I don't agree with sizing a steamer to EDR, as you already know we've had that argument many times.

I also don't agree with two stage gas valves, it gives you a ton of excess O2 most of the time you're running for no reason. There's no need for "extra gas to heat piping".

Regarding excess EDR, do you still have that excess when no longer running at steam temperatures, or do you now have undersized radiation, even at 180F?

Gordy

Does everyone approach their sizing like this article?
https://shar.es/1EDw3L

Taking Another Look at Steam Boiler Sizing Methods

Sent using ShareThis


Sent from my iPhone

Gordy

Let's look at your system Chris. What is your boiler DOE output, what is your EDR, and what is your heat load?

ChrisJ

@Gordy if you want to continue to beat the horse start another thread on it. I'm not going to continue to hijack this one over it.

Gordy

Fair enough.

New England SteamWorks

Hatterasguy said:

...a mod-con conversion might be considerably more costly than a steam system upgrade, but I'm not even convinced of that.

To quote General McAuliffe: Nuts.

But at least you got the conversation headed in the right direct: Not what's hypothetically more efficient, but what is the most cost effective approach for a real customer in a real home with an actual steam system.

Erin Holohan Haskell

I sense we're straying into a larger discussion/debate of hypotheticals. Let's keep this thread on point or start a new thread. Thanks!

Steamhead

Hatterasguy said:

You have no argument on efficiency when a steam system is compared to a mod-con. You ought to stay on what you do know..............a mod-con conversion might be considerably more costly than a steam system upgrade, but I'm not even convinced of that. A full NBP change is probably more costly than the mod-con.

Actually, we do. Since a hot-water radiator of a given size only gives off roughly 2/3 the heat as the same size rad on steam (not hypothetical, but a FACT that was established generations ago), often a mod-con must run at higher temperatures to heat the building when applied to existing steam radiation. This means that it won't be condensing nearly as much as you think, which means its efficiency will drop. This is yet another reason why I advised the OP to stay with steam. Doing so is his best choice.

Brewbeer

I generally consider it to be bad form when folks post that some people shouldn't participate in a discussion. It doesn't foster a free flow exchange of information or ideas. Instead, folks should support what they post with supporting information so others can review said posts and info and draw their own conclusions. This site and all forums like this where people go to gather information function best when ideas supported by data are freely exchanged and discussed.

Erin Holohan Haskell

Brewbeer said:

I generally consider it to be bad form when folks post that some people shouldn't participate in a discussion. It doesn't foster a free flow exchange of information or ideas. Instead, folks should support what they post with supporting information so others can review said posts and info and draw their own conclusions. This site and all forums like this where people go to gather information function best when ideas supported by data are freely exchanged and discussed.

I agree. Thank you, @Brewbeer. Well said.

SWEI

There is one very real consideration which must be taken into account before any potential conversion: The piping and radiators must be pressure tested before you (or any contractor) can make an informed decision. Standard practice would dictate 60 PSI (2x the relief valve rating) for 24 hours, but you should probably start lower than that to avoid potential excitement.

Gordy

Before going through a pressure test I would do an EDR (Equivalent direct radiation) survey to be sure that the in place EDR can handle the heatloss at the reduced btu output of a water based system.
Typically 240 btus a square foot for steam, and 150 btus a square foot for a hot water system using 170 AWT. With that being said steam systems will inherently have less radiation due to their higher output because of higher system temps. Unless your home has had some substantial envelope upgrades then the EDR may fall short for a water base conversion.

All this can be done on paper before touching the system mechanically.

Steamhead

Hatterasguy said:

The assumption.............. is that they don't have any data and have nothing to support.

What possible value can they add to the thread?

Plenty, if you actually read the other thread I referred to. Here is the link again:

http://forum.heatinghelp.com/discussion/145002/actual-savings-over-steam-heating

In this thread, the OP describes a job where he ripped out a steam system in a larger building and installed hot-water using mod-cons. He did not mention how much, if any, of the original piping and radiation was retained. The only comment he made about the original system was that the fire-tube steam boilers were "well maintained", but did not go into any detail. He describes a 1/3 reduction in fuel usage, but does not establish a suitable baseline, i.e. the condition of the steam system as a whole, to give us perspective.

This is a common problem that I see every time such a conversion is written up. The comparison is between a broken-down steam system that is on the verge of total failure versus a brand-new hot-water system. This is not a valid comparison, never was and never will be. I remember one such "study" in a school, where all the outdoor controls had failed, and instead of fixing the problem, they were cycling the steam boilers manually! How is that a fair comparison?

Going back to that thread, I replied that my company repaired and upgraded a steam system in a 32-unit co-op apartment building with proper air venting and an outdoor control that actually worked, and achieved a similar fuel saving and comfort level for a lot less cost, complication and risk. And we still have the utility bills on file that show the savings. You want data? That's data.

Most of us, when we post fuel-savings figures, make a point of documenting the system as found and the improvements we made that resulted in the savings. To do less would be a disservice to everyone on the Wall. Let's see some of your fuel-savings figures, along with details of the systems as found and what you did to improve them.

jumper

It's not about "blinded by steam" . It's what to do in an old building. In the seventies I was involved in switching from steam to hot water in multi-floor buildings. The goal was less and simpler maintenance. The conversions turned out to be more problematic and expensive than expected. And down the road hot water has issues too. Looking back I think we engineers did a disservice to the owners.

Tinman

My vocation, and sometimes my avocation, is all things regarding hot water and radiant heat but steam absolutely fascinates me now that I've finally made the jump.

This ongoing, never-ending debate reminds of something else taking place in our society right now. What separates the two, in my mind, is that in the case of Hydronics both options are awesome. There's not a single person in this country who would say the same about the choices in the other scenario.

At some point it just boils down to opinions, preferences, what we know best, and unfortunately the insatiable need to be right. For me, there's room for both steam and hot water.

ChrisJ

I'd like to know when it's actually worth the owner paying for the labor and materials required to convert a single pipe steam system to a two pipe hot water system.

Just how bad would the system have to be, to justify that cost?

Seems like no matter what, it would be cheaper to fix the system and install a new cast iron steamer.

Tinman

Ok, I'll bite.

I'm not doing the math though because it's my day off and I already did it and I'm not at the office now.

The last conversion I did ->

Existing 800,000K steam boiler sized to the connected load, 78-80% AFUE at best. Boiler was shot and so was 100% of the returns throughout the building. On average, 1 pipe repair clamp per foot of pipe.

Heat loss of building was much less. We installed 2 cascaded KHN199 boilers, 10:1 turndowns, 1/2" PAP home-runned to each radiator. Basement had wide open ceilings so that was relatively easy.

I'm not saying this is the best solution every time but it was for this one and Chris was just asking for one.

Have at it.

Steamhead

That system was already demolished by neglect, which proves once again that you can't fix stupid. That was undoubtedly quite an expensive project resulting from lack of maintenance.

Then there are the hot-water systems that freeze up and burst............

Tinman

Agreed. It cuts both ways.