Should my furnace be pre-heating my hot water?

Users who are viewing this thread

ChimeraKC

New Member
Messages
1
Reaction score
0
Points
1
Location
Rockland Maine
Two questions actually - A few years ago when we bought our home, we got a new Bradford White Aerotherm water heater that has a heat pump. Told its very efficient.
What they did though was have the incoming water come through our oil furnace and radiator system - and the furnace keeps the water in there heated pretty high - it comes on now and then for a couple minutes. 24/7. But we turn it off in the summer - we are in Maine - so this is really a winter concern.

We were told that it was set up this way so that if there was alot of hot water demand, the heat pump would have water already heated from the furnace. Two things about this - its just two of us, rarely if ever is there a lot of hot water demand - its a pretty big tank too- but more important why would I want my less efficient oil furnace heating my hot water that goes into the way more efficient brand new hot water heater?

Second question - in the winter, when the heat is coming on more, is it more efficient to have the furnace coming on and off to keep the water that will circulate to the radiators warmer?, or just let the system turn on and off from the thermostat which means the water is being heated from a cooler temperature?

I am also going to speak to the heat pump company. Thanks for any help.
 

Fitter30

Well-Known Member
Messages
3,145
Reaction score
506
Points
113
Location
Peace valley missouri
Bradford white wh is where its located is the space heated? If the space gets cold the heater will run on the electric heating elements and not the heat pump driving the operating cost up. Cast iron boilers like to be kept warm with return water (water coming back to the boiler) 135° or warmer. Outdoor reset control can be added to boiler it will vary water temp on outside temperature. At 0° house might need 180° at 50° need 155° and shuts the boiler off at 65° - 70°. Boiler in the basement any heat when system isn't calling for the boiler isn't wasted going up into the house. Taco and others make E series pumps that are more efficient using a ecm motor. If and when you might need a pump.
 

WorthFlorida

The wife is still training me.
Messages
5,057
Reaction score
806
Points
113
Location
Orlando, Florida
Well established contractors in a given area usually knows what works best for their climate and install things for better performance and comfort.

It seem strange to me but I'm no plumber. I think what happened is you probably have very cold inlet water temperatures. Right now I'm in West Dover, VT and the well water is in the 40º's. Heat pump alone probably would not be able to meet hot water demands and it needs to be set for the electric elements to kick on when the demand exceeds the hot water demand (Hybrid mode). The contractor who set the system up and maybe from other customers receiving complaints during the winter months was a lack of hot water because many program the water heater to HP only. It also might be the cost of electric might exceed the cost of your furnace fuel to heat the water during winter use. Contractors do not like complaint calls under warranty because of lost of revenue and the system is working as designed especially during extreme cold. So things get tweaked to minimize these type of calls.

If the WH HP is in an unheated space like a basement, the contractor may have felt the ambient air is too cold. I could not find the specification for ambient air temperature for your model.
Second question - in the winter, when the heat is coming on more, is it more efficient to have the furnace coming on and off to keep the water that will circulate to the radiators warmer?, or just let the system turn on and off from the thermostat which means the water is being heated from a cooler temperature?
It's almost a mute point. To keep the home warm by heating water takes the same energy. Heating the water from a colder temperature or keep the water warm before heating up to temperature for home heating, the difference will be the standby lost and the efficiency of the furnace. In standby with warmer water the heat is lost into the home anyway. For me the bottom line is comfort, one way or the other. It may take longer to bring the cold water temperature up to heat the home therefore the temperature swings might be noticable.

If the system is working fine for you and the cost is not of concern, leave it as is. Normally water heaters are separate from your home heating system. Is there any way the bypass (installed valves) the furnace to bring the cold inlet water directly to the WH without doing plumbing changes? Hopefully the contractor did install valves should the furnace ever needed service or replacement, you would still have running hot water. If yes then give it a try with the WH in Hybrid mode.
 
Top
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks