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[Elguano]

Looking to connect my hot tub on the boiler, anyone have advices? About 400 Gallons, Not sure which Heat exchanger to use, I see the 88kbtu is recommanded for this size of tub, but am not sure about the connection, they are only 1" on the tub side,, and my whole hot tub is 2". If i want to keep 2", i have to go on a 300kbtu heat exchanger which might be too much.

Also connection wise, i was thinking of connecting a 3 way valve on the heat element, so when the hot tub ask for heat, the 3 way valve open, send the water from the boiler to the heat exchanger and when it reach it's temp, it will be just looping the flow from the boiler, any advice on this?

Thanks guys,

[E Yoder]

I'd use the small heat exchanger, tee the tub piping so a percentage goes through the tube and shell.
I wonder if the power to the element could trip a relay  to run a pump or zone valve.

[Elguano]

Well sorry for the late reply ! After a bit of trial error, yes you definetely need to T the line to the heat exchanger, connecting it inline have too much flow restriction + the tub was heating up too quickly and was shutting off thinking the element was dry...

And a 3way valve work if you plug it on the element, you just have to be carefull on which phase your connecting it too, the tub controller only switch off 1 phase for the heating element on/off circuit.

But so far we are 2 months with and the 5kw heating element as been off