Central heating, hot water, am I being a bit thick here?

[dancingmyrtle]

Ok, so we recently had our boiler replaced, along with a new 3-port valve and pump. The thing is, whenever we set the programmer to heating only, and leave the water switched off, we still get the water in the immersion tank heating up, and it gets very, very hot. Much hotter than when we have the programmer set to water only, and I can't help thinking it's costing us a great deal to heat all this water that we don't need. I've asked two plumbers and an electrician, and they all say it's working as it should be, but surely I should be able to heat the radiators without the water heating up too, I used to be able to do this?

[Lucisky]

I am not a plumber or electrician, but that is not right at all. Of course the water shouldn't heat up if you have got the water heating set to 'off' on the controller. Something is wrong, so you need to get the original installer back to have a look.

[PigletJohn]

it could well be the 3-port valve, or the wiring. The installer is probably responsible.

To get an idea of what is happening, feel the pipes going to the valve. The upright of the "T" comes from the boiler, and will be hot whenever it is firing. One of the arms goes to the cylinder, and one to the radiator. Identify which is which. Put the Heating on and you should feel the pipe to the radiators quickly heat up. Put the HW on and (provided the cylinder stat is calling for heat) you should feel the pipe to the cylinder quickly heat up. You should hear the 3-port valve whir when it moves from heating/hot water/both. You may also see a lever on the side of the motor box move. Look at the lever to check it has not been left at the "manual" position. Yours is most likely an ACL Drayton or a Honeywell. You may be able to identify it here. It will probably be the 22mm size. 28mm valves, found on older systems, are more expensive and have one extra wire to connect.

Also look at the thermostat on your cylinder. It should be set round about 50-60. It must always be set lower than the boiler thermostat.

If either of the pipes is hot when the controls say it should be off, the 3-port is not working correctly. New valves are unlikely to be faulty so it is more likely a wiring error. What do you know about the qualifications and experience of your installer?

You haven't got an electric immersion heater turned on, have you?

[dancingmyrtle]

Hi PJ, immersion heater defnitely not switched on. We've had an electrician in to look at it and he was adamant that it's all wired correctly and couldn't understand my problem. I have suspected all along that it's a faulty valve, despite it being new.

It was installed under the ECO boiler grants scheme and the installers are reluctant to come back and look at it, I can tell that they don't understand my problem and think it's all working as it should. They say I should get a local plumber to fix it and then invoice them, but I'm worried that I'll never get my money back.

It's good to hear, though, that it's definitely not right. We thought we were going mad!

[PigletJohn]

some people say that the companies installing heating under the grants have a contract with a rock-bottom price that isn't enough for skilled staff to do a quality job.

however somebody is paying for this, and it's a poor show if work is shoddy. You might like to try the grants company.

[dancingmyrtle]

Thanks PJ