Radiant floor hot water loop off steam boiler test mode

ethicalpaul

Here’s my first shot at my hot water loop for my 5x7 foot “master” bath 😂

I had run exactly 100’ of Uponor 5/16” radiant tube (including the up and back distance) into their fast track panels under my new tile floor a couple years ago but waited for my new boiler to pipe it in.

right now it’s just test mode with a light switch on the grundfos 3-speed circulator. The aquastat is in place but not wired. I have a thermostat wire and a slab temp sensor in place but not yet connected. I have a Honeywell T6 Pro coming from eBay.

I like to work in stages so next I’ll wire up the thermostat with a Relay in a Box for the circulator.

Initial tests show .4 gpm regardless of speed setting so I’m on “low”. About a 10 degree delta T with around 140F at the manifold supply. This gives me about 85F floor temp depending on if you’re standing over a tube 😅

This Uponor manifold is very cool, it has all the bells and whistles.

It’s amazing how much heat energy the boiler stores. I can run it several hours with only around 30F loss of boiler temp. There’s a lot of iron in a Peerless. 

Posted in Strictly Steam because by far the most interesting part is the interaction with the steam boiler. Hit me with all your comments, you know how I love a discussion.

Jamie Hall

Looks good! I like your approach to these things, too, @ethicalpaul

ethicalpaul

Thanks @Jamie Hall! You have taught me a lot since I’ve been here!

Here is the floor after running the loop for an hour or so. The incoming water got a little hot, like 150F before I switched off the circulator.

it looks dramatic but the temp spread is only 16F.

KC_Jones

My grandfather was a mechanical engineer, my father is a mechanic who worked in power plants for 32 years. Both of them taught me that doing things in stages is almost always a good idea because it allows you to identify a problem long before it gets out of hand.

I agree, your simplified approach to a complicated system is a good one. I also feel one learns a lot more doing it this way.

I am very curious how it will work long term with actual boiler water going through the tubes. I'd like to do this in my own home in the near future, but I was planning a heat exchanger, you have me rethinking that.

neilc

ODR mixing valve ?
don't you want or need one ?
or did I miss it in the pictures?

ethicalpaul

Hi @neilc— I’m using just a manual valve on the bypass to add just enough resistance to the bypass circuit to let some boiler water come in.

It’s on the vertical pipe partially closed

ethicalpaul

I had my first interesting thing happen.

When the circulator is OFF and the boiler is ON, heat will start to travel from the boiler, up the bypass, then to the pex return (which goes to the wet return) and also over toward the manifold (to the left around the chimney).

Is this just heat flow like out of a water heater without a trap? It all gets quite hot including the length of pex (which is well above the waterline so that’s a bit confusing to me), so I closed the valve at the boiler for now.

I’m considering a check valve or a heat trap nipple (but I think the check valve can handle way more heat so I’ll probably go that way).

Thoughts?

ethicalpaul

KC_Jones said:

 I am very curious how it will work long term with actual boiler water going through the tubes. I'd like to do this in my own home in the near future, but I was planning a heat exchanger, you have me rethinking that.

Thanks @KC_Jones! 

I’m really curious too! This article here on HH discusses the issues involved with using boiler water: https://heatinghelp.com/systems-help-center/how-to-run-a-hot-water-zone-off-a-steam-boiler/

I was really attracted to the simplicity and reduced cost of foregoing the heat exchanger.

According to industry standards I should be using a bronze pump but at about 1/3 the cost I just had to try iron once!