1 zone space heating, 1 zone DHW. Crowdsourcing opinions.

JohnNY

Weil-McLain EG water boiler already in my possession.
Tankless coil optional. The section is in place to accept the coil.
I'm thinking I like the idea of setting it up for single zone heat and using an insulated storage tank with the tankless coil and a pump for the DHW.

Tell me why I'm wrong.

Of course, the other option is to set it up as two zones and ditch the coil idea.

Ironman

Will you have to use the triple aquastat to keep the boiler hot to heat the tankless coil? That would use a lot more energy than doing an indirect as a second zone.

Zman

I see the 2 options as a horse apiece.
You either buy an HX in the indirect tank or you buy a tankless coil. Bob makes a good point about idling the boiler although a clever guy like you could turn off the boiler when the tank is satisfied.
I think I would go the indirect route unless I was going to use an electric heater for storage and turn the boiler off during the summer months.

Solid_Fuel_Man

I like the electric water heater as a storage tank, with a bronze pump and the tankless coil. Use the electric element in the summer and turn off the boiler. In the winter use an aquastat bulb under the tank's insulation to trigger the bronze pump and fire the boiler, operate it as a cold start. 

EBEBRATT-Ed

If you use the coil you need another expansion tank and a feeder and a pressure relief valve which you don't need with a standard indirect hook up. You need a circulator either way.

Probably get more flow through the indirect without the tankless. Tankless coils are restrictive

mattmia2

If it is cold start, make sure you have enough indirect capacity to wait for the boiler to heat up.

JohnNY

Solid_Fuel_Man said:

I like the electric water heater as a storage tank, with a bronze pump and the tankless coil. Use the electric element in the summer and turn off the boiler. In the winter use an aquastat bulb under the tank's insulation to trigger the bronze pump and fire the boiler, operate it as a cold start. 

I like this a lot except for the price of electric being what it is in New York. Interesting though.

JohnNY

EBEBRATT-Ed said:

If you use the coil you need another expansion tank and a feeder and a pressure relief valve which you don't need with a standard indirect hook up. You need a circulator either way.

Probably get more flow through the indirect without the tankless. Tankless coils are restrictive

All good points and exactly what I was looking for. Indirect water heater it is though I like the idea of a tankless coil soaking up energy passively as it sits in a boiler between firing cycles.
Thank you all very much.

JakeCK

JohnNY said:

Solid_Fuel_Man said:

I like the electric water heater as a storage tank, with a bronze pump and the tankless coil. Use the electric element in the summer and turn off the boiler. In the winter use an aquastat bulb under the tank's insulation to trigger the bronze pump and fire the boiler, operate it as a cold start. 

I like this a lot except for the price of electric being what it is in New York. Interesting though.

Might be more than the budget allows but look into a hybrid heat pump water heater. I just bought a 50 gallon to replace my aging 40gallon gas and so far I have been happy with it. It uses a comparable amount of electricity to my dehumidifier. I have it set to heat pump mode and so far it has been able to keep up with the demands of two adults showering back to back, baths for small kids, and a load of laundry an hour or so afterwards. And if the heat pump can't keep up the electric elements are always an option. When using it in the summer it will also help cool and dry the house.

As a side note I'm powering it with a PV system. I have a schedule set to raise the temperature to 130 in the am when the PV really starts producing power and have it drop the temperature after 4pm and shut it off completely after 9pm. Poor mans Tesla battery.

lkstdl

JackCK that's a neat idea. Are you using an external timer to schedule it or is that functionality built in to the water heater?

JakeCK

I'm using the econet app from Rheem. However I was able to integrate it into my home automation system as well. A time of day based schedule works for now but eventually I want to write up something more advanced that takes into account projected/actual solar production and length of day light. Or might get a better light sensor outside.