Add HWC to sealed system

[Vaci]

I currently have a simple sealed, pumped heating system with one zone, a timer control for the boiler and TRVs on all the radiators. However, the hot water cylinder is electric only via the immersion, and a long way from the boiler.

I recently replaced the cylinder, and with foresight installed an indirect one. I now have an opportunity to run a connection to heat the HW from the boiler somehow - but routing the pipework is tricky!

The easiest solution appears to be to treat the HWC as just another radiator, and tee it into the existing circuit just before the final radiator (which is the closest one). Is this a possible/sensible solution - how could I control the HW temperature? Or am I going to have to bite the bullet and find some way of running a new zone all the way back to the boiler?

Vaci

[Andy Cap]

What are you going to do in the Summer when the heating isn't required ?

Andy

[Ed Sirett]

It would be contrary to Part L or the building regs to install a stored HW system which did not have independent control of the time and temperature.

Without looking at the route for the flow and return pipes to the indirect coil I can say how easy this is for you. Plastic pipe, used wisely and correctly, will greatly simplify the running of pipes in suspended floors and/or ducts.

You will need full S plan controls (see main FAQ).

If you did decide to go for the simple method [1] then you would use a TCV (Thermostatic cylinder valve)[2] to control the temperature of the HW. You will find that if you don't need to run the heating enough then you may not get all the HW you require. However since you have a modern cylinder then you should be OK, although some of the nearby radiators or more may be robbed of heat while the cylinder is (re)heating. In summer and perhaps at other times you will need to go back to the electric water heating.

[1] Which I absolutely have never suggested you do... [2] Much like a TRV but with a remote sensing bulb that work on a cylinder temperature range (50C-65C).

[Vaci]

Yes, and would be annoying to operate, too. I think I'll just have to do the Right Thing.

If only I had any suspended floors or ducts! Alas my apartment block is built like a car park - concrete everywhere! Plus the flat layout is against me - the boiler in one corner, and the HWC in the far opposite corner, separated by doorways and corridors. Even to get the pipework from one side to the other will require going up into the suspended ceiling - which will require some carefully placed air vents.

[Cortina]

TRV's could stop the rads heating.

[Cortina]

Couldnt you have a 2 port valve controled by a cylinder thermostat and a timer? Youd need a mains supply from the boiler and a 'demand' wire back to the boiler. In any event you dont need to have the zone valves next to the boiler if somewhere more central is more convinent.