Hot tub + wood boiler (Alpha phase)

Norm Harvey

Hello guys!

  I was hoping that you could help me out with the design phase of a little project I was asked to undertake.

 Scope:

 The customer uses a outdoor wood boiler to heat  their home  through a plate exchanger that then uses the mechanicals of the oil fired system to distribute the heat.    If for some reason the wood boiler's fire goes out, the oil burner seamlessly  takes over the load.

  Since they have had such success with this,  they now want to have the wood boiler heat their hot tub  wich they use on a daily basis.

The plan:

   Currently, the wood boiler circulates its 200 gallons of thermal mass constantly through a plate exchanger.    I want to add a second one in series for the hot tub.  The hot tub is of course a lower priority so that plate exchanger will see cooler entry water.   But given that I am not looking for an output of over 100 degrees, series should be fine.

The problem:

   I am unsure of the capabilities of the hot tubs circulator, but I know that there is no way it can handle the load.  So,...  hydraulic seperator mounted near the hot tub?   Even then can a hot tub pump handle that?

 I dont work with too many hot tubs, so I am unsure of the tub mechanicals.





Thanks in advance

hot_rod

what about

a pool or spa HX. They have a large connection for the pool pump to run through, and they are built with the proper metals to handle the pool chemicals.



Also flat plate HXers are used for pool, typically with some bypass piping to assure flow rates.



Contact Flat Plate with the pool and pump size, and the expected temperature you can feed to the spa HX and they can size and built the exact HX for the job.



You might pipe them so the house gets priority, then the spa is treasted as a secondary load, instead of in series with the first HX.



A basic setpoint or differential control could make the decision.



hr.