Steam boiler - Add electric hot water heater??

Steve_in_NH

I have a steam boiler with tankless coil installed. I decided to add a electric hot water heater so the boiler wouldn't need to run in the summertime. I read multiple post that said it could be done, but none explained how. I just jumped in and did it. Well, I'm having an issue with water pressure in the hot water supply. Cold is fine.

The setup: Pretty simple, I connected the mixed hot from the boiler to the cold inlet to the water heater and connected the cold line to the mixing value coming out of the water heater. I also added temperature gauges so i could monitor the temp going into the water heater and out. The existing hot piping from the boiler is 1/2", cold is 3/4", I didn't change this.

Was this a mistake? I'm doing more research now and still can't find exactly what I'm looking for but some of what I'm seeing is making me second guess this setup. I'm also thinking that maybe I'm just missing a circ pump?

Any help would be great!

pecmsg

What fuels the boiler?

KC_Jones

Did I read correctly that you are going through 2 mixing valves all the time?

ethicalpaul

I do think it was a mistake. I would just cut any connection between the boiler and the water heater and let the water heater heat the water and let your boiler heat your house.

Hopefully you considered a heat pump water heater, but if not that, then hopefully a Rheem Marathon plastic-tank well-insulated traditional electric heater.

Steve_in_NH

Yes there are two mixing values. The existing one at the boiler set to 120, comes to the water heater about 110 (water heater is located on the other side of the house), water heater also has mixing value, temp on water heater is set to 140 with mixing value set to 120.

It's an oil fired boiler.
Yes its a GE heat pump water heater.

EBEBRATT-Ed

Too much restriction with the tankless coil and 2 mixing valves.

I would skip the tankless. You would have to spend $$ for a circ pump and controls to use the tankless to preheat the water temp in the heat pump water heater

ethicalpaul

OK sounds great on that heat pump water heater. I agree with @EBEBRATT-Ed. Just let the water heater heat the water.

Steve_in_NH

Thanks for the advice.

"You would have to spend $$ for a circ pump and controls to use the tankless to preheat the water temp in the heat pump water heater" - What would the process look like to add the circ pump and controls?

Robert_25

Good advice above - and something else to consider...running cold water through your tankless coil when the boiler is sitting cold is a recipe for condensation in the boiler.

Steve_in_NH

Okay thanks, sounds like i should make the switch back. Any opinion on setting it up so i can switch back and forth between the two. Use the boiler to heat water in the winter and the water heater in the summer. It would be pretty easy to setup. I've got the necessary shut-off values already installed. Just need to tap into the hot line.

jumper

Steve_in_NH said:

Okay thanks, sounds like i should make the switch back. Any opinion on setting it up so i can switch back and forth between the two. Use the boiler to heat water in the winter and the water heater in the summer. It would be pretty easy to setup. I've got the necessary shut-off values already installed. Just need to tap into the hot line.

You know what you're doing but will the next guy?

Steve_in_NH

I’m more worried about any on foresee issues. Such as if both are open at the same time without knowing. What would happen. I’m thinking mixed water of unknown temp from the boiler mixing unmeasured with the 120 from the water heater would be the biggest issue. Would it cause any other issues such as the drop in pressure I wasn’t expecting with the other change.