Adding new Boiler

ecurbjk

Hi All,

I have a small underfloor heating setup and the primary hot-water source is a 10 gallon tank heated by solar. It heats the water up to about 90 degrees F into the loops and 80 degrees F on the cold return, feeding 4 loops about 250 feet each. I purchased a new Thermolec 3K mini boiler and air separator to add to the system. I need some advice on the correct location of the new boiler and separator. Can I feed the hot water outlet from the hot water tank to the cold inlet of the boiler and then the hot outlet of the boiler to the loops. The cold return from the loops would feed the cold of the hot water tank? see attacked pic. Also, what would be the best location for the air separator?

If my thinking is in correct, any help will be appreciated.

Thanks

Bruce

Jamie Hall

Is that expansion tank on the INLET side of the pump? I hope so.

Otherwise the general concept looks good.

Kaos

I would install the boiler on the hot feed to the floor heat loops. Set the boiler to a temperature bellow what your solar can deliver. This way the boiler will only run if solar is not putting out enough heat.

Something like solar tank→air sep→pump→boiler→heating loop.

GGross

just saw you are keeping the solar disregard my drawing

ecurbjk

Yes , the expansion tank is on the inlet side of the pump. I read the pumping away book.

So from the comments, it sounds like I maybe on the right track with:

solar tank hot outlet → air separator → pump→ boiler inlet → boiler outlet → heating loop hot → heating loop cold return → expansion tank → pump → solar tank cold inlet.

Are you suggesting a second pump?

Thanks

Bruce

,

hot_rod

Is the solar a closed loop glycol system with a solar heat exchanger or solar tank?

Also, turn the Grundfos so the motor faces out, when you make the changes.

ecurbjk

I have a 4 kilowatt solar array that keeps my Pytes batteries charged and Victron inverters that send AC to the 10 gallon water tank. If I have a day or two of no sun I need the boiler to kick in.

To add the boiler to the setup is this correct:

solar tank hot outlet → air separator → pump→ boiler inlet → boiler outlet → heating loop hot → heating loop cold return → expansion tank → pump → solar tank cold inlet.

hot_rod

The Sun Bandit is a clever approach to PV- DHWH. PV power directly to the tank, eliminate the inverter hit.

You can buy DC elements if you shop around and build your own PV dhw tank.

There are piping or control methods to let you use either or, or even both at the same time.

A Resol controll has all these functions built in.

https://sunbandit.us/

Kaos

https://forum.heatinghelp.com/discussion/comment/1870295#Comment_1870295

Pretty much. Move the existing pump to the supply (hot water outlet) side, you don't need a 2nd one on the return.

Out of curiosity, what are you using as the diversion controls?