In Floor Heat. What do you have?

Raspy · Feb 4, 2012

KB9UDE said:
How deep in the concrete do you bury the pipes? I am looking at doing a job requiring heat in the floor and was not sure if it was to be laid on the insulation board or suspended in the concrete??

It's tied to the reinforcing mesh or rebar and, as long as it's contained in the thickness of the slab, it's not an issue where. Just make sure it isn't below the slab in some areas and contained in others. This can happen if it gets stepped on during the pour and left pushed down into the dirt. Also, having it right at the surface makes it more vulnerable. Since most slabs are about 3 1/2" to 6" thick, and the installation method is consistent throughout, it's a non issue.

JCByrd24 · Feb 4, 2012

DRL said:
The 12kwh figure is when the heater is running wide open. My Hydro Shark has a indicator light that says when it is modulating or wide open and it can go for weeks before I see it running wide open.

Another thing to remember, a kilowatt is a kilowatt. There is very little difference, usage wise, with different types of electric water heating. The "CLAIMED" savings for tankless water heaters is the heat loss of the stored water in the tank. Not really an issue when using them them for heat.

DRL

This is absolutely correct. If you are heating with electric it's going to be the same cost no matter what, all systems will be around 99% efficient. Tank or tankless doesn't matter, the tank is loosing heat to the space your heating, nothing wrong with that. I would guess a regular electric water heater would not heat that building because as has been said they're normally like 4500 watts (15-20,000 BTU/hr and you need 40,000). I know electricity is cheaper in some areas, but it'd have to be really cheap to even compete with oil/propane. My choice would be easy. Pellet boiler. Easier/cleaner/requires less attention than wood, also very cost competitive here. Obviously if you have lots of acreage and wood, wood boiler.

jimgerken · Feb 6, 2012

KB9UDE said:
How deep in the concrete do you bury the pipes? I am looking at doing a job requiring heat in the floor and was not sure if it was to be laid on the insulation board or suspended in the concrete??

Depth in the slab causes a trade-off in response time and heat spreading effect. To demonstrate, imagine two systems: system one has the tube at one inch deep (measuring down from the top of the slab surface), system two has the tube at the bottom surface of the slab. the slabs of both systems are 4 inches thick and have 2 inches of extruded polystyrene under them. System one will have hot and cold lines detectable on the surface to the bare feet or hands. It will respond in a few hours if the thermostat is changed. System two will have very even heat distribution on the surface. It will take twice as long to stabilize after changing the thermostat.