Hot water radiators and temp swings...

[KungfuRabbit]

Hey!

I have hot water baseboard radiators and old school thermostats, so I was shopping for a smart thermostat. The HVAC guy I talked to said for hot water you can't aggressively have temp swings to save money, and you are better if holdin temp steady, or at most letting temp drop 3-4 degrees.

He couldn't say why, anyone know a scientific reason for this?

[bacchi]

It's more efficient to let the radiators get cold while you're away.

If you're gone for a while, the water and room temps will equalize. Whether you raise the water temp all at once or throughout the day doesn't matter.

http://homeenergysaver.lbl.gov/consumer/faqs#wh3

[ShoulderThingThatGoesUp]

I have steam radiators and I appreciate how the Nedt learns how much the hot radiators will heat the house after the furnace shuts down and shuts it down earlier to compensate. Not an answer to your immediate question, but tangentially related.

[KungfuRabbit]

Yea I understand the math is simple, colder is cheaper, but he thought there was a different reason. Perhaps it's hard on them and you'll breakit sooner?  Idk, maybe he was just wrong.

And yea, that's why I wanted a Nest, they are slow to respond so need something smart.

[lakemom]

I will say that our boiler/pipes/etc. are all original to our house built in 1961.  We keep our daytime temp at 66 with a bump to 67 during evening downtime then drop to 62 overnight bringing it back up to 66 about 30 minutes before we get up for the day.  Everything works just fine and it only takes about 30 minutes for the house to warm up from 62 to 66.  We just have a programmable thermostat (about 8 years old now) bought off the shelf at Lowe's.  I've often heard its "harder" for hot water heat to warm a space up but we moved here from a home with gas forced air and like the baseboard heat better.