DIY Doctor UK DIY Forums

Back in June I wrote such a long post that no-one replied. Not surprising really; it was quite an essay. I hope I might pique someone's interest with a much shorter version :)

Basically, I want to install a central boiler to run a number of radiators on one circuit and a Japanese-style bath on another. The bath would be heated via a swimming pool heat exchanger or similar. In concept, this is not so different from a domestic hot water circuit -- when the bath is 'on', hot water should circulate through the heat exchanger under the regulation of a sensor reading the bath water temperature.

I live in the centre of Portugal and will have to do this myself. I'm quite confident of my ability to install a basic central heating system and solve this secondary problem. (The pipe runs for the central heating are already in place.) However, I realise there are a number of things I do not know about central heating systems/boilers.

Basically, I know the controller will need to open the valve (to the bath circuit) and turn on two pumps (the primary and secondary sides of the heat exchanger). It will also need to activate the boiler. But I have no idea what kind of signal is needed to turn the boiler on. In fact, is one needed at all (or does the boiler sense that water is flowing and that the inlet water is below a set temperature)?

Any insight, or links to somewhere I can find out more about designing central heating systems, would be very welcome...

Thanks,

Steve

You need to research the boiler... Most appliances will have a switch live requirement...


Thus....



Controls tell the valves when to open and close; the valves are fitted with microswitches which then provide a 240v signal back to the boiler to turn that on/off.


Here in the UK; pool boilers are a completely different beast to that of central heating ones... If you need to common the two; then you'd use a plate heatexchanger to perform the heat transfer from one circuit to the other.

Hi

I would suggest that you treat both circuits (1 X Heating & 1 X Pool) independant of one another. This means two systems but a common heat source. A DTR controler can be used for your bath and will look after the temperature of the pool, temperature of plate heat exchanger, switching of pumps & boiler. You will need a control valve for each circuit and a pump for each circuit. You can also get controls for the central heating circuit and any air conditioning you may have. Not a cheap soloution but the correct one and I suspect a fraction of the overall project cost. On the plus side you will recoupe the cost in fuel savings at some stage. Also worth thinking about solar panels as they would keep runing costs down and because ot the amount of water involved pay back periods are reduced significantly.

[quote="GeckoGas"]



Controls tell the valves when to open and close; the valves are fitted with microswitches which then provide a 240v signal back to the boiler to turn that on/off.


[/quote]

Thanks! That's what I needed to know. So the controller/thermostat simply needs to open and close the valve.

It's a bath (like a hot tub) I'm talking about, not a swimming pool. Heated via a heat exchanger. I'm hoping to add it as a separate circuit -- in addition to a regular central heating circuit. It sounds like I'd use a completely separate controller for the bath circuit -- hopefully there'll be something off-the-shelf that can take input from a bath temperature sensor.

All I need to do now is source suitable components here in Portugal :)

Steve