Hydronic heating loop (boiler or water heater?)

Dooverdixon

Hey all,

My original plan for heating my basement was to install minisplits for the 800 sq ft of conditioned space, but now I am intrigued by the idea of creating a hot water loop for cost and efficiency.  I'm in the unusual situation of having multiple options.  I have an oversized dunkirk boiler that has just had all the mains repiped; during which we removed 2 of the burners to help with the oversizing issues.  I also have a commercial water heater 75 gal 75000btu that is designed to have a recirculation circuit for "combo heating"

What makes more sense to utilize from an energy efficiency, ease of install, effectiveness standpoint????

My brain tells me to leave the boiler alone and use the hot water heater, but I want to bounce it off the experts
(al

hot_rod

Radiant ceiling or walls?

A heat exchanger on the water heater would be my choice. The tank volume would buffer a small, low load zone nicely.

Taco use to have a mixing block with the two pumps and a plate HX and the control, if that is still avilable, it is a simple connection.

You have one connection already on the tank up high, remove the drain and install the connection there.

Or if you run the recirc pump 24/ 7 just add a plate HX into that line. I suspect you have a low load requirement. The B side gets a pump and a thermostat to operate it. Air purger, expansion tank, purge cock, very simple. A #15 expansion tank probably plenty for a single zone small system.

Dooverdixon

Thanks for the reply...and very nice drawing!!! Haha.  I'm thinking 20,000 to 25,000 btu would be sufficient.  And probably baseboard hydro radiators would be the easiest way to do it???

I love the idea of using the recirculation line/pump but, I feel like the water from the backside of the recirculation pump would be too cold?  But that is a super easy way to do it...assuming that little recirculation pump would be sufficiently powerful????


Im assuming you think heat exchanger would be preferable to using the actual water from the hot water heater to heat the baseboards?  I ask becuase the instruction manual actually shows using the heater water directly.  

Any idea what that taco product would be called?  

Dooverdixon

https://www.supplyhouse.com/Taco-RMB-1-Radiant-Mixing-Block?utm_source=google_ad&utm_medium=Shopping_tm&utm_campaign=Shopping_TM_New_users&gad_source=1&gclid=Cj0KCQiApOyqBhDlARIsAGfnyMrq8Hc7pJ6MYE6qxeSIPf8G_OGD75PXhtyQ_ZbOQ7AvaqmF7E7kac0aAlhYEALw_wcB

Is this the guy?   Pretty cool that it's all one unit.  

hot_rod

800 sq feet of basement? I'd guess below 10,000 btu/hr. Ideally you could do a heat load to know for sure what you are trying to deliver. the pump, HX, piping, radiant all should build around the specific "job" aka the heatload.

I think the "X" block is the version with the HX inside. A bit $$ but if you want the "package" and the tekmar ODR control...