Hot water gives me C/Heating

[Dan]

A couple of weeks ago I posted that whever I put my H/W on using the control panel I also got central heating. After a bit of investigation it was suggested that it could be the actuator/motorised valve not turning properly.

Anyhow, I managed to get a new actuator today, and before connected it to the valve (which turns freely by hand) I wanted to see how it should work.

When I put CH on, the D shaped connector moved 90 degrees. When I turn it off, it goes back 90 degrees. However when I put HW on it does nothing.

So anyhow I fitted it, and after 10 mins, it looks like I'm getting CH when I just put HW on (as well as getting HW).

So if it's right, and I'm not jumping to conclusions prematurely, its not the actuator and I still have the same issue, so what is my next course of action?

Also, just out of curiosity, on my water storage tank, what is a decent temp to set the thermostat at? It goes from 20 through to 90 degrees.

Kind regards, Dan

[Dan]

Oh, an update, maybe I'm just being silly. If I put HW and CH on at the same time, the D thing turns 45 degrees. So it looks like it should be working.

Dan

[Set Square]

Yes, that's right. The valve has 3 positions - HW-only (0 degrees), HW+CH (45 degrees) and CH-only (90 degrees)

With CH-only selected, and with the system running, unscrew the actuator from the valve and see what position the valve is actually in. If it's in the CH position but is passing water to the HW circuit, it sounds as if the paddle inside the valve is shot. *How* freely does the spindle turn by hand? If it's *very* free, it would re-inforce this possibility.

If the valve is actually in the HW or HW+CH position, there could be a wiring or programmer problem.

60 degC (140 degF) gives nice hot water - but not hot enough to scald. If you have a normal non-condensing boiler, the boiler stat (and hence the water going to the radiators) should be set at around 80 degC.

[Christian McArdle]

60C for a standard/mains hot water cylinder. 75C for a heatbank.

If you've got a standard/mains cylinder with a thermostatic mixing valve, you can increase the storage up to 75C or 5C below boiler temp (whichever is lower). This increases storage capacity and resistance to legionnaires disease, at the expense of some drop in efficiency.

Christian.