Heat exchanger for hot tub.

Hi Don. It could pose a safety risk and invalidate any warrantees, allegedly. I must admit if I needed to heat my own tub I may well have thought about giving it a go... where you actually put the heating coil could pose a problem. However, my 30 years of heating and plumbing experience thankfully prevents me from even trying. Good luck, Bob.

In theory yes you could but if you set your thermostat in the house to 23'C (for example) your house would have reached temperature long before your hot tub heated up. You could close all the TRVs on all the radiators in the house thus only supplying the heat exchanger in the hot tub but your boiler will run continuously until you switch it off when the hot tub has reached temperature and this isn't good for the boiler. You can of course also insert a zone valve and additional thermostat in the hot tub... Etc. Not a hot tub person myself but sure sometimetng similar its been done before. Good luck.

Best way to heat up a hot tub is with a air source heat pump Cheap to run and heats up with in 10 mins from cold