Pre-heat water for hydronic baseboard

mhixson · 09-28-21, 12:28 PM

My house has a propane heated hydronic baseboard system. Our propane prices fluctuate while our electricity costs are fairly constant. I'm wondering about getting a tankless electric water heater to pre-heat the water going into the hydronic system. My reasoning is that it requires more propane to heat 50F city water to boiling than it would to take 120F to boiling coming from the tankless heater.
Has anyone done this sort of thing before and did you see significant savings in propane costs?
Thanks!

u3b3rg33k · 09-29-21, 05:41 PM

what are your prices for kWh and propane? what temps do you actually run in the boiler?

nibs · 11-01-21, 10:48 PM

You should not be heating with cold city water, you must recirculate the water.
My hydronic system has a delta T of from 10 to 15 degrees F (the water returning to the boiler only needs heating by about 10 or 15 degrees)

09-28-21, 12:28 PM	#1
mhixson Lurking Renovator Join Date: Jul 2011 Location: Washington State Posts: 15 Thanks: 0 Thanked 0 Times in 0 Posts	Pre-heat water for hydronic baseboard My house has a propane heated hydronic baseboard system. Our propane prices fluctuate while our electricity costs are fairly constant. I'm wondering about getting a tankless electric water heater to pre-heat the water going into the hydronic system. My reasoning is that it requires more propane to heat 50F city water to boiling than it would to take 120F to boiling coming from the tankless heater. Has anyone done this sort of thing before and did you see significant savings in propane costs? Thanks!

09-29-21, 05:41 PM	#2
u3b3rg33k Apprentice EcoRenovator Join Date: Mar 2018 Location: Rustbelt, USA Posts: 114 Thanks: 5 Thanked 10 Times in 9 Posts	what are your prices for kWh and propane? what temps do you actually run in the boiler?

11-01-21, 10:48 PM	#3
nibs Apprentice EcoRenovator Join Date: Jun 2010 Posts: 206 Thanks: 1 Thanked 18 Times in 17 Posts	You should not be heating with cold city water, you must recirculate the water. My hydronic system has a delta T of from 10 to 15 degrees F (the water returning to the boiler only needs heating by about 10 or 15 degrees)