Hot Tub/Jacuzzi Heating

[musszzy]

I have recently purchased a hot tub which is heated via the Electric. The result is 11.5 kw of Electricity used daily just for the Tub. I have decided this is too costly and have started searching for alternative heating.
I have been looking at a Bowman EC80 Heat Exchanger which connects to your Central Heating System.
Has anyone installed similar systems?

I have some queries on whether this can connect directly to my pressurised combi boiler as some of the examples show header tanks.

Also rather than heat the whole house would i be right in assuming i would fit a three way valve to divert the heated water through the heat exchanger for the pool feed , although by doing this i am unsure how the return would feed back to the boiler unless you would use two three way valves to create a seperate circuit in effect.

Thanks for any input.

 

[ianmcd]

How do you plan on cutting into your hot tub for the flow and return ? on the primary side two 2 port zone valves would be your best bet, one on the flow to your home and the other on the flow to the tub heat exchanger.

 

[musszzy]

I believe i can find adaptors to fit the existing pool connections although i haven't looked in to this yet. So two separate valves i assume this wouldn't cause an issue if both the pool and Ch operate simultaneously however would a mid position valve not achieve the same result? Am I right in believing the return can just be plumbed in to the existing return?

 

[ianmcd]

yes a mid position valve can perform the same function, and yes the return can be plumbed to the existing return as close as possible to the boiler, you will have to have some kind of thermal cut out fitted too so that the water in your tub does not get too hot , the electrical system will probably shut off at 40C most of them do so you will have to wire in something similar to close the valve to the tub and shut off the boiler , that is why I suggested 2 x 2 port spring return valves rather than a 3 port mid position valve

 

[Martin62]

I'd start by looking at how well insulated it is. That seems quite a lot of heat loss. Is there any way you can add extra insulation? Normally the panel sides just have a thin sheet of foil lined bubble wrap type material. That could always be increased with putting rigid insulation between the frame work. We are working on system for topping up the heat via a small solar thermal panel and will be testing on my own hot tub.

 

[ianmcd]

Solar thermal panel in Inverness ??? what day does that work its bloody baltic there

 

[Martin62]

LOL, you would not believe how many times people tell us it doesn't work up here. We are at Latitude 57 which is the same as one of the biggest solar thermal plants in Europe, situated in north Denmark.
We do a lot of research & development work on solar thermal and believe me it DOES work really well. We get very clear skies especially in the winter. Have lots of clients using it up here.
Have a look at the attached sheet we made up, it shows it does work

 

[motorbiking]

If this is an outdoor arrangement, I'd look at options to improve the heat loss via additional insulation. Its costing you about £2 a day to run your tub.

How do you plan to make your solar thermal work? They are simplest as pre-heaters, which isn't going to work in your scenario. Will you get many days with +35 degrees in your panel?

 

[PullerGas]

Solar thermal panel in Inverness ??? what day does that work its bloody baltic there

It's a good day if you don't end up with an ugly ewe up there..........baaaahhhhhhhh!!!

 

[PullerGas]

A couple of cheap Chinese solar panels would give it a good pre-heat on a reasonably sunny day.

My mate who well minted, he's got a big Hot Tub out the back. I built him a big insulated lid for it & connected a SS Plate HX from his house F&R. Works a treat!! He also has two Russian bints he bought on-line, they keep him warm too!!

 

[Martin62]

Our design will be to just top up the heat requirement and not heat it all from cold. I would start with improving the insulation
a 1250ltr hot tub would require almost 47kW to heat from cold to 38ºC so no point in using Solar thermal for that. A 3kW immersion would take about 16hrs.