Thermostat setting for Hydronic Heating

[Black_Z28]

Hello all, this is my first winter at my new place with a extra detached garage that has hydronic radiant heat. I've pretty much got the system all up to snuff over the past few weeks. It was low on water, air separator was bad, reaplaced a pretty antiquated thermostat, ect.

So, something that is kinda cool is I can look at my real time electrical consumption through my electrical company. And, I've noticed when the radiant heat is running in the garage. And it's a pretty heavy spike, which I fully expected. But, I'm wondering if it's more efficient to have the thermostat set higher, so it runs more often? Right now it seems to run at night, which again makes sense. And it'll run for a few hours(maybe 5-6 hours each night). I'm sure because it has to heat the water in the pipes, then the concrete, then the structure to get to my set point.

I guess my theory is if it runs more often, the liquid in the lines won't cool as much so it won't have to run as long to get to my set point on the thermostat. Is this correct thinking? Or am I overthinking this?

Just looking for any advice.

Thanks

 

[finn]

Your thinking is wrong.

The higher the thermostat setting, the higher the room temperature, and the higher the room temperature, the more heat loss through the walls and roof to the atmosphere.

Heat loss is a function of delta T.

 

[LS6 Tommy]

Do you have a circulating system with a bypass, or does the t-stat just run the pump and boiler on a call for heat?

Tommy

 

[75gmck25]

I don't know how configurable your system controls are, but my house's hydronic system with radiators has several different settings to optimize the heat (low water temp, high water temp, etc.). My radiator hydronic runs at a higher water temperature than in-floor, but I assume the controls are similar. Your system also has much higher mass in the concrete floor than I have with radiators, so temperature rise will be slower.

We use a setback temp of 64 degrees at night from about 10:00 PM until 6:30 AM. Our Honeywell thermostat has a configurable "anticipation" function that turns on the boiler early so that it should reach the set point by 6:30 AM, and it is usually warm by the time we get up.

If you are going to only use your heat every once and a while, it will save you money to set the room temp fairly low until you plan to use it. The water and the slab will still be warm, but only warm enough to maintain that lower temperature. Then turn up the heat a few hours before you plan to start work, and turn it down afterwards.

Bruce

 

[Black_Z28]

Do you have a circulating system with a bypass, or does the t-stat just run the pump and boiler on a call for heat?

Tommy

Sorry, been out on business.

But, it's a pretty simple system. The T-stat just calls for the pump and the boiler to crank up.

I just kinda thought sense there was such a void between times it kicks in, that if I set the stat higher, it wouldn't have to play catchup as much when it did fall below the set point.

 

[stingry]

I just kinda thought sense there was such a void between times it kicks in, that if I set the stat higher, it wouldn't have to play catchup as much when it did fall below the set point.

All setting the thermostat higher will do is increase the temp in the room. Sounds like your system is working as it should. The radiant slab cools off very slowly and also heats up slowly, mine heats up about a degree per hour. The temp of the slab is only a few degrees warmer than the air temp. Here’s how mine works: my thermometer is set at 65*, so when it calls for heat, the pump comes on, sending 105* water into the loops. Initially the return water is about 65*, but fairly quickly it settles in at 85*, giving me a delta T of about 20*. Don’t try to second guess your system, let it do its job.

 

[Black_Z28]

Sounds good guys. I appreciate the knowledge.