staple up radiant, setback vs steady temp?

[4acrefarm]

I have a staple-up radiant with aluminun plates. I have a pararell wood-oil system. I have 5 zones, some rooms are used contstantly some are used 1 to 2 hours per day. My wood boiler is home built and undersized, my storage is also undersized. I have programmed t-stats to ramp up to peak at primary use periods in some zones and relativly constant in others. I hear all the time that radiant being slow should not be set back. Laws of physics are simple, "heat travels to cold" and "the rate it travels is faster the greater the difference in temp".shouldent a cooler room lose less heat to the outdoors? isnt that what we are shooting for? Any thoughts?

 

[sgschwend]

If it works and you like it then it sounds like you have a good solution.

I also use setback, about 5-8 degrees depending on outside temps.

Yes, one of the main variables in heat loss calculations is based on the difference in temperature, the small the difference the slower the heat transfer.

 

[stee6043]

In addition to how fast you loose heat you should keep in mind how long (and how much heat) it takes to get those cooler rooms back up to temp.

I've always heard on the news and in media that you should shoot for a setback of 10% (ie. 70 in the day to 63 at night). In my experience 10% is WAY too much. The amount of work required to heat all of the thermal mass in your house back up to a comfortable temperature seems to exceed the savings generated by the cooler "setback" period.

I've fiddled with my system more than I care to admit. I've managed to zero in on 4-5 degree setback being the most that makes sense in my case. And I think some on this site will share similar experiences. When you start pushing 6, 7, 8+ degrees your system has to work too hard to get back....in my humble opinion.

 

[ISeeDeadBTUs]

I messed with setback for my staple-up/wet-laid PEX. IMO unless we are talking more than 24 hours, setback is a waste. Similar to you, my wood-fired hydronic is somewhat undersized. That is HELL when all six zones are on at the same time! In theory set back might cause the same situation.

I do some MANUAL setback for rooms we use occasionally.

Jimbo

 

[flyingcow]

My staple up is on full tilt until spring(130). My baseboard is on a 6 dgree set back from 10pm until 6am. takes to long for the staple up to recover, set it, leave it, works for me.

 

[stephenmoore]

I agree with flying cow, i've experimented with various setbacks for my in joist retro fit zones and I really don't see any savings in fuel. Even setting back 4 degrees seems to take forever to get back to temp. and by then you are ready for bed and setting back again. I think the best part of all in floor is the consistency in temp and comfort you get from leaving it set. My degrees are celcius by the way.