hot water heats rads when heating is off

[fancyabrew]

I have a Worcester-Bosch Heatslave 12/14 When the hot water is on but the heating is off the rads can get very hot (if hot water is set full on) any ideas whats going on?

Kerry

[John Rumm]

Your three port/zone/divertion valve is probably stuck...

A bit more informationon your system would be required to tell you much more.

[meow2222]

too many possibilities, too little information

[John]

Check that the motorised valve hasn't failed. Happened to me last week.

John

[fancyabrew]

Ok little more info.

Heatslave 12/14. 5 rads in total on three floors, boiler in the basement with three rads on ground floor and 2 on first floor. Heating works fine as does the hot water. If the heating is turned of completely, but I have the hot water turned on, the rads can get VERY hot, especially if I have the hot water turned up to 5 for running a bath etc. Bolier has been in for about 2.5 years , pressure is fine.

[Roger Mills (aka Set Square)]

Not being familiar with this particular boiler, I'm not sure whether it's a combi - or whether you have a stored hot water system (hot cylinder in the airing cupboard). We need to know which it is - because the diagnosis is quite different, depending on the answer.

[fancyabrew]

its a combi

[John Rumm]

So, when you turn on the hot tap the boiler fires up, but the water comes out of the tap cold and the rads get hot instead... does that sound about right?

If so the diversion valve inside the combi has probably failed.

[fancyabrew]

Nope, hot water works fine, BUT when the hot water circuit is on the rads also get hot even if the heating circuit is turned off. I noticed this over the weekend when I had the hot water switched on to run a bath for the misses. We have a very high flow rate as we're at sea level so I always switch the hotwater control to 5 to make sure the waters good and hot. The heating was switched off at the time as the house wasn't cold, but after a while I noticed the room getting a little warm and when I touched the rad it was bleddy hot as were all the rads in the house!

[John Rumm]

OK, I am having difficulty resolving your "hot water circuit" and the bit about having a combi boiler (i.e. one that heats hot water on demand) and also talk about high flow rates seems out of place (given the power of the boiler mentioned).

Could you confirm if you have a hot water cylinder in the house?

[Thorn]

You could try Worcester technical helpline, or send an email enquiry -

will give you the number or the email address (sorry can't remember tech helpline off the top of me head)

Thorn

[Ian White]

We had the same problem in a Heatslave combi a few months ago. The diverter valve gets a lot of exercise in a combi, especially if you're in the habit of using frequent short bursts of hot water (eg to rinse individual pots and pans). When ours was in the process of wearing out, it went through a period of making little thoughtful noises, and finally stuck part-way with exactly the same symptoms that the OP describes.

[fancyabrew]

that sounds about right. Rough cost to get fixed?

[Ian White]

(presumably about the diverter valve)

The boiler repair got swept up into the bill for a much larger plumbing installation, and only seems to have cost about £45 + VAT! As a one-off job, you'd obviously have to pay a lot more.

[fancyabrew]

we've got a couple of plumbers here at work and they seem to think its a stuck valve, expect a bill of up to =A3200 I've been told. Oh well call to worcester comming up

[Doctor Drivel]

we've got a couple of plumbers here at work and they seem to think its a stuck valve, expect a bill of up to £200 I've been told. Oh well call to worcester comming up

Have a look and see if the 3-way valve is easily replaced. If it can be, then it may be worth it to do it yourself.

[Roger Mills (aka Set Square)]

So just where inside your one of beloved *combis* are you going to find a

3-way valve?