Domestic hot water and in floor hot water heating.

[jcarhart]

I have a 15 year old combined hot water in floor heating and domestic hot water system. I do not think the 2 systems are isolated from each other. I have one oil fired hot water tank that I am having problems with and want to replace it with either an electric tank or a propane fired tank.
Should the domestic hot water be separated from the in floor hot water?
Do I need 2 new tanks?
How would this be plumbed in?

 

[Mitchell-DIY-Guy]

My own personal opinion is that I'd prefer to have them separate (domestic hot water, and radiant in-floor heat) UNLESS you have all kinds of extra capacity in your hot water source.

A typical hot water water, natural gas, has a burner capable of maybe 40,000 BTU/Hr; that's not nearly enough to heat a home in many climates by itself. In my last house the furnace, modulating, was 40K-->100K BTU/Hr. That's just the furnace, the hot water was separate. However, does your system (aside from the "troubles" you may be having with the oil fired hot water tank) work fine? If so, just replace that tank with one of equivalent ratings. Somebody did a reasonably nice installation job, it's hard to find a nice job without some thought behind it.

If I'm not mistaken, propane will probably cost a bit more to run than fuel oil, and electricity will be out of sight.

 

[jcarhart]

My own personal opinion is that I'd prefer to have them separate (domestic hot water, and radiant in-floor heat) UNLESS you have all kinds of extra capacity in your hot water source.

A typical hot water water, natural gas, has a burner capable of maybe 40,000 BTU/Hr; that's not nearly enough to heat a home in many climates by itself. In my last house the furnace, modulating, was 40K-->100K BTU/Hr. That's just the furnace, the hot water was separate. However, does your system (aside from the "troubles" you may be having with the oil fired hot water tank) work fine? If so, just replace that tank with one of equivalent ratings. Somebody did a reasonably nice installation job, it's hard to find a nice job without some thought behind it.

If I'm not mistaken, propane will probably cost a bit more to run than fuel oil, and electricity will be out of sight.

Thanks Mitchell: Our in floor radiant heating only heats the basement floor and the attached garage. We have a oil fired hot air furnace for the rest of the house. Running out of hot water has never been an issue. The oil fired hot water burner issue is fixed, I think. It required its yearly maintenance. My concern is should the domestic hot water and the radiant floor hot water be separated?

 

[Mitchell-DIY-Guy]

Again, my own opinion: if it's all working fine, don't go through the effort of adding yet another heating source to fire the floor heat...
All working fine? No hot water supply issues (not running out?) then just leave it all alone. Looks like a nice install job.

 

[packardv8]

We've been heating the floor in a sunporch with a dual outlet gas water heater for twenty years now. Since a concrete slab doesn't gain or lose heat rapidly, it doesn't "consume" hot water like running a tub full. We never notice any lack of hot water we can attribute to the floor heat.

As to separating them, our code does not require separating the systems when new installations and PEX tubing. We've again had no problems we can attribute to a single source system.

jack vines

 

[jcarhart]

We've been heating the floor in a sunporch with a dual outlet gas water heater for twenty years now. Since a concrete slab doesn't gain or lose heat rapidly, it doesn't "consume" hot water like running a tub full. We never notice any lack of hot water we can attribute to the floor heat.

As to separating them, our code does not require separating the systems when new installations and PEX tubing. We've again had no problems we can attribute to a single source system.

jack vines

Thanks Jack. I appreciate you letting me know.