Hot water heating rookie

[laney.graphics]

Never really messed with radiant hot water heating, so maybe I'm out of my element, but I have a smaller garage area, approx 16x26, that I'm thinking of adding radiant water heating to. only asking as I have all of this available to me, but not sure it will work properly. I have a propane tankless water heater setup from upgrading the house setup. I also have a hanging radiator with electric fan, and access to a few cast iron radiators, each about 2ft long x 3ft tall. My question is if the water heater which I think has a max temp of 140 would be enough to heat my small area? or do I absolutely need something upwards of 160-180? Finding mixed reports online but would like to make it work, even if I need to source a different heater. the area is well insulated, r19 walls, r49+ ceiling

 

[yeldogt]

Never really messed with radiant hot water heating, so maybe I'm out of my element, but I have a smaller garage area, approx 16x26, that I'm thinking of adding radiant water heating to. only asking as I have all of this available to me, but not sure it will work properly. I have a propane tankless water heater setup from upgrading the house setup. I also have a hanging radiator with electric fan, and access to a few cast iron radiators, each about 2ft long x 3ft tall. My question is if the water heater which I think has a max temp of 140 would be enough to heat my small area? or do I absolutely need something upwards of 160-180? Finding mixed reports online but would like to make it work, even if I need to source a different heater. the area is well insulated, r19 walls, r49+ ceiling

You need to do a simple heat load on the building -- but that is not a big space. The question would be setting up cost -- running cots and the cost of doing a mini-split and the running cost of that. Where are you located ?

 

[laney.graphics]

You need to do a simple heat load on the building -- but that is not a big space. The question would be setting up cost -- running cots and the cost of doing a mini-split and the running cost of that. Where are you located ?

im in central Minnesota, forgot to put that in my original post

 

[fitter30]

High efficiency boilers are only high efficiency when return water is 130° f above 87% doesn't matter what brand. Cast radiators normally run 160° + systems design for 20° drop between supply and return temps. What is the depth of the radiators. Take a pic of one. Brand and model of heater take a pic of name plate.

 

[PoorUB]

It will work, but you need something like 3x the radiator that you would need for 180 water. Beings it is such a small space you will not need a a lot of radiator. Also, personally I would not bother worth the cast iron radiators as they take up so much room and use fin tube baseboard instead.

How large of water heater do you have? It is probably huge in regard to what you need. 10,000 BTU will heat that space and my bet is that water heater is well over 100,000 BTU.

IMO, but the time you get done screwing around with it a 30,000 BTU Reznor of Modine will be less money to put in an way less hassle, and even if the water heater s a 90+ efficiency I doubt you would notice much difference in your gas bill.

Even a small direct vent wall heater would work well. I might consider a Empire DV215SG with a fan kit.

 

[75gmck25]

I guess radiator design temps must have changed over the years, since my 1940 home has cast iron radiators and the system runs at a max temperature of 140 degrees. I always thought the 180 degree systems were for baseboard heat, which loses heat quickly when the thermostat cycles it off. But cast iron radiators have so much mass that in the winter they never really cool off.

When my Buderus boiler shuts down it maintains a standby temperature of 100 degrees until heat is called for, and then it turns on the pump and starts heating the water. If use a setback thermostat to turn the heat down at night to about 4 degrees, the boiler never even hits 140 before the house is warm. I did try a 10 degree setback for a while and found that the system then got up to about 140 degrees by the time the house had recovered.

The radiators I got for a new addition are Myson and they don't have anywhere near the mass of the old cast iron. However, I used their BTU tables to size them for a 140 degree system and they seem to work very well. They make for a nicer installation because they mount on the wall and leave the floor clear.

 

[PWC Repair]

Hook the water heater up to the hanging rad. You will need a small pump if you don't have one, and a $30 expansion tank. It will be closed loop and you'll want some anti-freeze in it. Hook your t-stat up to the pump. When the pump comes on, the water flows and heater heats. It will absolutely heat that small space.

 

[Jackfre]

What make is the water heater? Takagi is the only manuf who approves their water heater for use in hydronic applications. ALL others have rescinded their approvals. When I repped Rinnai everyone wanted it to be a “boiler” and used the water heater as such. It was problematic and they consumed vast qtys of propane. For a space that size in MN I think you should look at a Rinnai EX22 Direct vent wall furnace.

 

[75gmck25]

delete

 

[Mzungu]

What make is the water heater? Takagi is the only manuf who approves their water heater for use in hydronic applications. ALL others have rescinded their approvals. When I repped Rinnai everyone wanted it to be a “boiler” and used the water heater as such. It was problematic and they consumed vast qtys of propane. For a space that size in MN I think you should look at a Rinnai EX22 Direct vent wall furnace.

Exactly this.

 

[nadogail]

During the 1950's my employer used to send me to a radiator shop in Anchorage, Alaska where the shop was heated by the "Hot Tank" they used to strip the paint and grease from the radiators they D-8worked on. The shop was heated by running hot water through a Cat D8 radiator.