Message: Hi Alan: I bought a 155 titanium pool heat exchanger from you a few months ago and am using it to heat our 525 gallon hot tub from our oversized domestic solar hot water heater (direct pv pump).  It works fine and now I have a customer who wants me to do one for him.  So to make sure I am doing it most efficiently, I have some questions, if you could be so kind to answer so I can start getting my parts together: 1.  Is the 155K overkill, or a good size for a hot tub?  I am trying to provide most, if not all the heat from this while using an insulated cover. 2.  Should I be using the same recommended flow rates for hot and cold loops as for larger pools (5.8 and 66)? 3.  What circ pump do you recommend for the heating loop from solar storage tank to HE?  It is about 60' and I plan to use 3/4" copper. I plan to have 145 gallons of storage that I should be able to get up to 160F plus with (3) 4x8 flatplates, depending on season.  We are at latitude 23 and it never gets below 50F and seldom below 60. Any suggestions will be appreciated.  However I am reluctant to use evacuated tubes since we are in a hurricane zone, and I am more comfortable using FP's for our warm and very sunny  climate. Thanks and best regards,  Skip

Dated on : 07-26-2012

Replies :

Skip, yes the 155K is the correct size for a hot tub application and the 3 solar panels.  I would suggest the flow rate on the hot tub be the regular circulation flow rate that the hot tub pump produces.   As for the pump on the solar loop, I would suggest a Laing E5 solar pump.  These are extremely efficient and are magnetically driven so there are no wearable parts.   Dan

Post By : Dan Jung Dated On : 07-27-2012