Heat Exchanger for DHW-Wiring Diagram?

Cyclist77

As I continue my Wintertime planning of moving from a coal stoker boiler to a CI NG boiler I was wondering if someone could help me with a diagram?

I would. Ike to consider a HX setup as this would allow me to continue to use my current DHW setup. I understand I need a pump on both sides of the HX. Would a yone help me out with a simple wiring g diagram?

Btw,I would pipe it in to be able to descale.

Thanks!

jesmed1

@Cyclist77 And your current DHW setup is…what?

@EdTheHeaterMan is the wiring diagram guru when he is not backup singing…

EdTheHeaterMan

Is your current system still the Wood Boiler with the electric water heater tank?

That HX idea from a gas boiler is easy to wire…. I want to know what gas boiler you have decided to use? That will determine what relay is your best option based on the boiler's onboard control system.

EDIT: for @jesmed1 : 🎶 Do-wop do be do. 🎶

Cyclist77

Yes, I am currently using a coal stoker boiler & electric water heater with a circulator on a timer.

The boiler I am planning on using is a Weil-McClain CGa4.

Kaos

There is a couple of ways of skinning that cat.

You can put the tank loop pump and the plate HX pump on the same circuit and fire them the same time when you get a priority call.

Another option is to put the plate HX pump on its own aquastat that monitors CH side. This way it will only run once the tank loop comes up to temperature. This is the setup I use with mine, use a cheap Inkbird control unit since I have a plug in pump.

Finally you can skip the tank loop pump and put the plate HX on the boiler loop. Any time the boiler is making water hot enough, the plate HX pump will run. When the boiler is off, the resistance elements will kick in. This will get you the bulk of your hot water off the boiler but keep you from having to run the boiler in the summer time.

EdTheHeaterMan

This should work. R8845U relay Lower thermostat from DHW tank to the T T on the R8845U to bring on both circulators and the burner. You will need to use a separate relay to operate the Central Heat zone(s). There may be some zone controls relays that can also do this but I will need to look at your entire system in order to get you the best wiring design to offer priority DHW

Cyclist77

TThanks !

hot_rod

Once you nail down a boiler choice it may have some of the functions you need built into the control. The DHW priority option is common on a lot of boilers these days. That gives you the pump and temperature control without additional controls.

Cyclist77

Meeting tomorrow with the hvac guy who is going to help me out. I will do all the heavy lifting and he will provide the wisdom!

Big Ed_4

Are you twining in the new gas boiler with the stoker and your hot water is supplied by the electric tank ?

Cyclist77

No, the coal stoker boiler will be retired! I had considered keeping it in the mix but we have had a 16 year run and it's time has come. I also will be removing 5 bins that each hold 1.25 tons coal. So right now I am in the process of running the coal supply down.