sparky472
Active Member
This is the hot water line out from my water heater. I'm going to be replacing the heater and the line, and came across this contraption on the line where it enters the wall. Anyone know what it is??
What is this on my hot water line?
- Thread starter sparky472
- Start date
Help Support Plumbing Forums:
Just a guess, but since it has spade connectors on it, I'de have to say its a sensor of some sort. Probably heat. Maybe to a thermometer? It's either a rheostat or a switch I would think.
I have never seen such a creature before.
Toxarch
Active Member
It's a thermostat sensor for a heat recovery unit. Do you see any cut off or closed off copper pipes in any of the walls close to the tank? Commonly called an HRU (Heat Recovery Unit) I believe. There should be two other copper pipes in the area that lead to the heat pump outside the house. Used to have 2 in my house. During the summer, your A/C heat pump draws heat from the house and exchanges it with the outside air. With a HRU water heater, it uses that Heat from your A/C unit to heat your water in the tank before it heads to the outside unit. It measures the heat in the tank via that thermometer in your picture. If the tank gets to the set temperature, then the heat (freon) from the A/C bypasses the water tank and heads to the outside condenser. It's a form of green energy and for a while you could get rebates for installing them in the house.
Problem is you need some special license to put them in or have to call the A/C guy to remove the freon, plumber to change the special tank out, then have him come again to recharge the freon. It makes your water tank and outside condenser more expensive and. They have slowly gone away even though they can save you a lot in water heater bills in the South during the Summer. Having one tied to a modern heat pump often voids the manufacturer's warranty on the heat pump. A family of 4 saves like $100 per year in hot water heating. A new condenser with a voided warranty costs more than that to replace.
Problem is you need some special license to put them in or have to call the A/C guy to remove the freon, plumber to change the special tank out, then have him come again to recharge the freon. It makes your water tank and outside condenser more expensive and. They have slowly gone away even though they can save you a lot in water heater bills in the South during the Summer. Having one tied to a modern heat pump often voids the manufacturer's warranty on the heat pump. A family of 4 saves like $100 per year in hot water heating. A new condenser with a voided warranty costs more than that to replace.
Last edited:
sparky472
Active Member
oh boy. I haven't gotten into the walls near the heater yet. So how on earth do I tell if one of these HRUs is installed? It looks like the sensor isn't connected to anything other than the pipe. Does that mean the HRU isn't connected/installed? My house was built in 92 but the heater is from 94. Clearly something went wrong with the original unit, and I wonder if this HRU you speak of was disconnected at that time...
Toxarch
Active Member
No wires so it's not HRU anymore. Count the pipes in the top of the tank. HRU tank has 4 pipes.
