Convert steam radiators to hydronic?

RayWohlfarth

Have you covered a steam system to hydronic? I have never done it myself. The old radiators have the steam inlet high and the outlet low on the other side of the radiator.

Thanks for your expertise

Ray

Jamie Hall

Good heavens, @RayWohlfarth — that's been talked about a number of times. I've never done it, but I know @Steamhead has… it can be done — but there are ptifalls.

JUGHNE

Are you converting an entire system or just some individual radiators?

mattmia2

They can't be steam only radiators, the sections have to connect at the top. They can leak at 15-20 psig when they didn't leak at 2 psig steam. I think those are the main pitfalls.

Steamhead

Actually, @Jamie Hall , I've never converted an entire steam system to hot-water. And I never will. Way too many pitfalls.

@RayWohlfarth , tell us a bit about the job, and how did they get such a bad idea.

RayWohlfarth

Thank you all. They have a 100 year old building and equally old steam system. The customer installed a new VRF system and the rooms at the end of the building can't heat in cold weather, like below 20 degrees F. The interior rooms seem to maintain temperature. The steam pipes are leaking and they asked if they could put in a hydronic boiler and pipe it to the radiators using Pex. They are looking to connect the boiler to four radiators per floor, two at each end of the building and the building is three stories high. Like I said, i never did this and hope to help the contractor avoid a lawsuit. I appreciate the help

Ray

hot_rod

If the top and bottoms are connected they will heat with hydronic flow.

With a conversion fitting they could just S&R at the bottom, with or without a TRV.

A 3 story building would have 12- 15 psi on the bottom floor.

Could be a lot of rust and sediment in them also.

Jamie Hall

https://forum.heatinghelp.com/discussion/comment/1804941#Comment_1804941

Didn't mean you'd done a whole system. You wouldn't, and for good reason. Like… many good reasons. Nor is it something I or most folks would recommend.

Seems to me, @RayWohlfarth , that your client's client or whatever would be best served if someone sat down and figured out first, why some of the radiators don't heat properly and, second, figured out why the steam pipes leak. There could be any number of reasons why some radiators don't heat properly, and most of them — particularly on two pipe systems — are both cheap and easy to fix.

The leaking steam pipes is a bit of a puzzle. They rarely do, as they rarely rust, except for wet returns (which do) and occasionally low spots. All of which should, again, be easy and relatively cheap to fix.

I presume by VRF system you are referring to a flavour of heat pump system — variable refrigerant flow? They're very nice. They may or may not play nice with an existing steam heating system — or one reconfigured for hot water. Whatever, fixing the steam or changing over isn't going to help problems with the VRF system.

mattmia2

Stem pipes usually only rust if the boiler is throwing liquid water up in to them.

DanHolohan

Ray, if the steam inlet is high, and the return is low then the radiator sections are connected both top and bottom. You could use those with hot water.

RayWohlfarth

@hot_rod Thanks I will look into it. By the way, I saw Hot Rods repair shop in WV and thought of you

@Jamie Hall Thanks, you bring up lots of good points. Yes it is a variable refrigerant flow system.

@DanHolohan Thanks Dan I appreciate it. I will let you guys know how it works

Erin Holohan Haskell

https://heatinghelp.com/systems-help-center/converting-from-steam-to-hot-water-heat/

RayWohlfarth

Thank you @Erin Holohan Haskell Youre awesome

Grallert

I've done a number of them but I really only use the radiators. Once I've converted them with a supply valve and return union I drop through he floor with 1/2 black pipe to preserve the look. I rarely used single entry valves. From there I used forsta pex and a manifold. This way everything in the living space looked somewhat original. If I had a leaker, which was rare, I would remove it, drain it flip it on it's head and fill it with hot water and sodium silicate and put pressure to it until it sealed up. Usually worked.

jumper

Changing the pipes is the big job. Why not change pipes but stick with steam? Radiators have more heating capacity with steam. I'd consult Igor about air elimination. Steam is more appropriate for large buildings.

WMno57

@Grallert Why? Seems like the conventional wisdom here is to keep it steam. Could you share more?

Were these repairs to get the heat back on, or upgrades to working systems?

Leaking returns, Leaking boilers?

Replaced with conventional hot water boiler or ModCon?

Client's idea or your idea?

Commercial or residential?

Any steam systems you feel are not a good candidate for this?

Thanks

Grallert

I have no problem with steam really and I've replaced plenty steam boilers. When I do a conversion it's for any number of reasons and the home owner gets all the info and makes the final decision. Sometimes a conversion doesn't make sense, that could be a cost issue. A conversion is more costly. Ease of control is a big one. I know there are folks who will say steam is easy to control, as easy as a modulating boiler with high mass emitters. But for a home owner I find that's not always the case. Another reason is space in the cellar and head room. Most of my conversions were from big cast iron to wall hung modulating condensing gas. If there are multiple floors the work gets harder. Getting water to the upper floors and keeping the "look" of originality is challenging.

I've only ever done residential work. Any systems that are not good candidates? That's a good question. It is or can be more costly to convert depending on the extent of the job. The work I did was complete, piping, valves, controls etc. everything to conceal the fact that there's been a change to the originality to the system. That might mean finding radiators to fit the period as well as make up for the fact that the water in the system will now carry fewer BTU's than the steam. So to the question. An 18th century ware house might be a struggle. Anything is possible but not always worth the cost or effort.

clammy

in the past i ve made my own conversion using a single radiator connection and made up a drip tube that would insert about 3/4 of the length of the radiator. Usually i would use a 1 1/4 x 3/4 x 3/4 and flare one end a 1/2 copper and inserted into a 3/4 close nipple and tighten the nipple usually i would cap the end drill 1/4 to 3/16 holes in the insert as to inject supply water into the rads sections it would help heat the rad evenly and prevent supply water from short cutting it and get better flow through the rad ,at least this how i have done it , the return side would be off the bull of the tee. The ones i have done as far as i know are still working fine ,had one i converted in a extra room for years till i finally purchased a 48 x 20 panel rad ,using low temps 135 max at design . It was much cheaper then the oventroupe valves which where available at the time and before such as supply house.com . i would go and ask about them at the supply house i dealt w and they would look at me like a 3 nipples billy goat and say never heard nor seen and i would pull out th catalog and they would shruge and say only you would ask for that lol. Have not made one in 10 years or more . For myself and customers i would really suggest new panel rads or new cast and avoid the pressure testing ,the flushing and the adding of wye strainers and magnetic separators especially w ecm pumps , and lets not forget some one who flush and check them w yearly maintenance which usually does not happen ? They do work as long as your not exceeding the piping flow rates so as to not evaluate your return temps at low temp. the one point to cast rads is that they hold the heat a panel rad will cool down quite quickly in comparison . Now what we really need is indoor air reset w constance circ and of course trv and a one zone system w one pump not a multi zone w multi stats and of course all the math was done so all work at one basic temp curve . Next lifetime dreams lol or a simple dung hut burning dung and adjusting to the environment like all other life forms . ok off the ballot box

peace and good luck clammy

Grallert

Single entry TRVs and a pump. So simple. When I first moved to western mass I was asked to quote a job like this and the guys at the supply house thought I was crazy never heard of such a thing. A guy named Dave at Premier Supply Group Knew what I was talking about. Now this train of thought is somewhat common.