Radiant heat of steam boiler

staron

Is there a way to run radiant floor heat of a steam boiler and if so how? I have a weil-mclain eg/peg-55, i re did the floor in the basement and put pex in the slab for for future radiant heat. Is there a way to run it from the return. I saw a thread about this a long time ago but i can open it to read it

Mad Dog_2

Absolutely 💯......   a few ways...Going to a Brunch..  check in later.  You'll probably have 10 diagrams by then!  Ha ha 😂..but Absolutely doable.  When people ask what are their heating options for a Bathroom 🚻 or Kitchen with Tile or a basement slab I say.. : "You Don't have a choice...I'm giving you Radiant!!!"  Mad Dog 🐕 

leonz

Speaking as a layman/homeowner/coal stoker boiler owner;

A single drop of water used to create wet steam expands 1,700 times.

A single or double drop header will create dry steam faster and deliver
heat to the radiators faster to heat them faster which will release the heat more
slowly.

The dry steam will send this heat into the radiators more quickly as it has
little if any condensate in the dry steam and they will shed heat back into
the living space for a longer period.

If your beautiful steam boiler does not have a great deal of
water in the steam chest it may not be at all possible to feed enough
hot water to heat the floor.

The other issue is if the steam boiler has enough water in the
steam chest would cycle more often and consume more fuel
if the slab is not adequately insulated also.

A steam licensed plumber and or a system design office of a
larger plumbing firm would have to look at your heating system
and the pex size in the floor and tell you if steam radiators would
be a better method of heating your basement instead of in floor pex.

You have to remember that every time you pull water out of the
steam chest to heat the floor you are lowering the water temperature
in the steam chest and the thermocouple will sense this and fire the
boiler.

Using small cast panel radiators would be a much easier way to add heat
into your basement by branching off the riser pipe to the upper floors.

If you have a one pipe system:
If you do not already have a single drop or double drop header in your heating system
adding a drop header or double drop header and the cast panel radiators would
heat your basement and increase your boilers efficiency.

I believe A 2 pipe system would require much more plumbing and pipe and any radiator
would have to be hung near the ceiling to allow for adequate drainage back to the
boilers condensate return tapping but I am not sure of this.

Big Ed_4

You want to pressurize a hydronic system to prevent air problems . A heat exchanger is used to move the energy from the low pressure side(steam) to the high pressure side (hydronic).. . With an modern shorter boiler with lack of large boiler taps below the water line for a gravity feed supply to the heat exchanger, a circulator is piped is from two of the bottom boiler taps ...

Jamie Hall

As @Big Ed_4 said, you really do need a heat exchanger of some kind between the boiler and the radiant for best results (though in some settings you can do without). However, you can do that -- and solve the possibility of having to run the steam boiler too often -- in a very simple way: run a hot water loop off the steam boiler to an indirect tank, which will serve as a buffer tank and the needed heat exchanger. Then run the radiant loops off the indirect tank. You can run the indirect up to a nice reasonable temperature -- say 140 or so -- and then draw from that with a pump and a mixing valve to give you a nice stable temperature through your radiant system. Could even have the mixing valve controlled by outdoor reset, if you wanted to get more sophisticated (would be a good idea).

Unless your boiler is undersized -- which is highly unlikely -- there should be ample capacity to handle the radiant.

Mad Dog_2

I've done radiant off of water heaters, coils, u name it.  Mad Dog 🐕 

EBEBRATT-Ed

As @Jamie Hall & @Big Ed_4 mentioned you need a heat exchanger, circulator, expansion tank , water make up prv and a 3 way mixing valve and a few other items to make it work. to make it work. Not cheap but doable

Mad Dog_2

I've done many, the Jimmy The Gent Burke way..the Economical, oil company way: 
No HX....downside: 
1) The dirty steam condensate wears hard on the standard Taco 007. 8-10 years life.

2) Will get air-bound if you drain the whole boiler down. 

When someone really can't afford radiant, and you wanna help them enjoy the beauty and comfort that it affords on a low budget.  It works and it could always be done the "better way" down the line, but atleast the tubing is embedded.   Mad Dog 🐕 

staron

Thank you everyone for the info. Or would it be more efficient if i would install a hot water heater or a instantaneous wall hung unit dedicated just for the radiant heat, its a 650 sq ft area am trying to heat

Mad Dog_2

Why don't you put up some pictures of your boiler and boiler room to see what's best for you.  Mad Dog 🐕 

Jamie Hall

staron said:

Thank you everyone for the info. Or would it be more efficient if i would install a hot water heater or a instantaneous wall hung unit dedicated just for the radiant heat, its a 650 sq ft area am trying to heat

Nope. And as @Mad Dog_2 implies, if your all your emitters are below the water level in the boiler -- you don't even need the fancy stuff. Just a couple of places to attach a pipe (best is a tap just below the low water cutout level and the return into the wet returns) and a pump.

Mad Dog_2

The radiant zones are usually always for a new bathroom 🚻 on the First or second floor or the kitchen in an average home 🏡.   Mad Dog 🐕 

staron

staron

Here are the pictures of the boiler room. I just want to know what would be my best option

Big Ed_4

Yes ..Condensation loop heating was first used to heat finished basements , below the water line . Normaly a single pipe system ...
Are you looking for the best option or the cheapest. That mud in your system caused by steam leaks, boiling off the water and leaving the solids behind . That mud will settle in the basement radiant tubing . Will it plug up ? .. Anything that could happen , will happen ...

Mad Dog_2

Just turns the Tubing brown..As long as you flush out mud every 6 months, which should be done anyway, it won't generally clog.  Mad Dog 🐕 

staron

Am looking for what would work best as far as price and efficiency, does it pay to run it of the steam boiler or would it be better to install another hot water heater dedicated to the radiant only. I assume installing a wall hung instantaneous boiler just for that would be too costly. But i dont necessarily want to go the cheapest route either. Am looking for advice on what would be best option in this situation since i dont plan on replacing the steam heating to hydronic no time soon

Mad Dog_2

How old is the water heater? Bradford White uses a Combi-Cor the same footprint a regular water heater but has a large coil inside that you can use for Radiant.  They work great on small to medium sized radiant zones and take up no extra space.  

A Separate Hydronic boiler dedicated to radiant only WILL add up fast.  Mad Dog 🐕 

ethicalpaul

Mad Dog_2 said:

Just turns the Tubing brown..As long as you flush out mud every 6 months, which should be done anyway, it won't generally clog.  Mad Dog 🐕 

That's been my experience too...at least in the Peerless, the water loop tapping is high enough that if your water is decent, you don't get anything nasty coming into the loop. And a screen filter helps too.

mattmia2

The trim you'd need for a second boiler is 80% of what you'd need to set up an isolated loop off of the existing boiler. If there is a tankless coil available for that boiler you could use that as the hx for the radiant and save the need for a circulator for the boiler side.

staron

Thank you everyone for info