Heat exchanger

[UKjames]

later this summer I plan to remove my now defunct mastertemp boiler and replace it with a heat exchanger that is powered by my house gas boiler.

Now my pool pad is about 1m from the outside wall of the house, down one side, so this means I don’t need to have a long run of pipes outside to lose heat.

The house boiler is 35kw which is about the same input as my pentair but it is much more efficient (allegedly) something like 80% vs 95%

So if I’ve got the radiators in the house on then the pool might not get the full 35kw. There’s also quite a long run in the house itself from the boiler to exterior wall but that’s going to be captured in the house as well as the 3ft of pipe that is going to be outside which will lose heat too

Freezing is a bit of a worry but if I run the heating circuit for the the heat exchanger then that should mitigate.

Setting it up to run on thermostat is going to be a bit tricky to automate so will likely be manual. I’m going to use Drayton wiser WiFi TRv heads to be able to turn on which radiators in the house or the pool heat exchanger as wanted. I’ve got a WiFi thermometer probe but that won’t be able to tell the wiser trv to switch off as the latter is going to be measuring the temperature in the pad shed rather than the temperature of the water flowing through the heat exchanger but I think I can live with that. I use i WiFi plug to control my pump and another for my swcg which seems to work pretty well. Again linking them to the wiser trv is unlikely to be possible.

 

[1poolman1]

Be sure the pool heat exchanger you want to use can resist damage from chemically treated pool water. Its nature, especially as it is heated, is much different from your domestic water that, likely, is going through your house boiler. Because of the chemicals we add, pool water is very aggressive.

 

[UKjames]

Be sure the pool heat exchanger you want to use can resist damage from chemically treated pool water. Its nature, especially as it is heated, is much different from your domestic water that, likely, is going through your house boiler. Because of the chemicals we add, pool water is very aggressive.

Thank you- there seem to be some specifically designed heat exchangers for pools. The same (or similar) as what go into certikin genie heaters. They are Either cupro-nickel or titanium. I think I’ll go for the latter.

 

[UKjames]

So an update. My new heating method is installed and working nicely and fully automated from my phone.

The setup is as follows:

Bowman titanium heat exchanger rated at 76kw. (You can get cupro nickel ones at slightly cheaper but figured for the faff plus double spend if it fails that I’d go for the more durable one. It wasn’t a massive amount more. )

The Bowman is then connected via 22mm pipe (it has a 22mm connection for heating water) to my central heating system. It’s electively just another radiator on my radiator circuit.

So how does this work in practice- I don’t want to heat my house for several hours whilst heating the pool. To get round this I could go round and turn all the house radiators off when heating the pool and vice Versa when heating the house but that would be a real pain.

Luckily I’d already got the house set up with a load of WiFi TRVs (thermostatic radiator valves). These effectively mean that every radiator is independently able to switch on and off and also tell the boiler to give it more heat. So all I had to do was put another WiFi trv on the bowman.

To heat the pool I turn on the pump and then use the heating app to call for heat to the heat exchanger. This is where there is a bit of a wrinkle, the trv only measure the temperature of the air around the heat exchanger (as it’s designed for a radiator that heats a room) so I have a separate WiFi thermostat with probe (there’s a pocket in the Bowman for the probe) to tell me what the temperature is (again via phone app) I then need to shut off the bowman’s trv (again via my phone) when it gets to desired temperature. This is a manual process so not ideal but the temperature increases fairly slowly so not a massive hardship compared to the cost saving of the setup Vs getting a new dedicated pool heater.

So, so far so good. It’s all automated but very much on a budget; I use WiFi plugs to turn on my pump and swcg and the WiFi trv to control when the heater is on.

I was able to do this as my pool plant Shed is only a meter or so from the side of my house so there wasn’t a massive lot of digging required to run heating pipes underground.

I also had a section of the heating pipe circuit running in the house next to the pool plant shed which again meant minimal disruption in the house.

Freezing of pipes is a concern but the boiler can send heat through them if it drops below a certain temperature ( the WiFi TRV will automatically turn on below a certain temp)

I’ve decommissioned my money pit master temp 125, which having researched a bit more wasn’t worth pouring more money into.