Two Radiators on when Hot Water on but Heating off

dark_star_3 · 3 October 2004 at 3:41PM

LOL @ Plumb 1, you sound like my old tech lecturer ;D

I agree, it sounds like a problem with the system motorised valve(s)
In many cases you can replace the motor part of the valve without the need to drain the system, but for all the reasons Plumb has indicated (ie all the system variations) I would recommend getting a professional in, best case scenario...get a known tradesman, recommended by someone you know and trust.
If you can get "unbelievables" plumber I would go for it...otherwise expect to pay about £100

plumb1_2 · 3 October 2004 at 10:45PM

It is 1 of 2 things,a faulty 3 way valve,or it has been piped up wrong,the return pipe from the Hot water side ,has been joined into the return pipe before the last radiator feed,thus getting a reverse flow from the hot water side.

Ticklemouse · 4 October 2004 at 11:24PM

I have to admit that I know nothing about plumbing, but at my last house and also at my mum's, the bathroom radiator comes on when just the HW is switched on. I think this is brill, as it means there is somewhere to dry your towels, and if you don't want it on at all, just turn the rad off. I always thought that this was designed like that. I miss it in this house, but now I'm back 'oop north', my heating is on more, so I've usually got somewhere to dry stuff

plumb1_2 · 5 October 2004 at 4:10PM

I have to admit that I know nothing about plumbing, but at my last house and also at my mum's, the bathroom radiator comes on when just the HW is switched on. I think this is brill, as it means there is somewhere to dry your towels, and if you don't want it on at all, just turn the rad off. I always thought that this was designed like that. I miss it in this house, but now I'm back 'oop north', my heating is on more, so I've usually got somewhere to dry stuff

The original system could have been on Solid fuel,and the bathroom rad would have been piped up as a heat sink,as there is little control on a solid fuel system

jackie_parish · 6 October 2004 at 1:15PM

WE HAVE BOUGHT A HOUSE WITH OLD HEATING SYSTEM IN IT (20YRS). WE PUT OUR WATER ON, AND WATER AND RADIATORS COME ON. IF WE PUT HEATING ON, NOTHING COMES ON.

When we had this problem in our old house it was the diverter. Fortunately we had cover so i dont know the cost of a replacement.

Hope you get it sorted soon i remember what a pain in the a**e it was.

Cheers

Jackie

robby-01 · 7 October 2004 at 6:29PM

could just need a none return valve fitting if it is a conventional system with gravity fed hot water.Simple job for a decent plumber.As mentioned before if pumped system[ ie y or s plan] fault could lie in faulty motorised valve.If system is a combi it may not be a fault as some send excess hot water away from boiler when demand ceases and pump it around heating system to disperse it.That is why a correctly fitted system will have at least one radiator without trv's.
hope that helps

plumb1_2 · 7 October 2004 at 7:21PM

.That is why a correctly fitted system will have at least one radiator without trv's.
hope that helps[/quote]

Not realy true,as most systems should have a bypass fitted,either auto or manual.
It is generaly old coal/oil fired systems that you have to leave one rad not fitted with trv,s mainly the bathroom one.
plus a answer to the original ? it could well be the programmer and not the diverter valve.What needs to be done is a electrical test to see which leads to the diverter valve is becoming live.

boofy_2 · 12 October 2004 at 11:40AM

I have this problem too. A couple of suggestions: (1) on the side of the pump (mine, anyway) is a black switch with 3 settings on it. I turned mine down to 2 which eliminates one radiator coming on. (2) phone round your local plumbing suppliers and get quotes for the part you need, you'll be surprised. That way you only have to pay for the work. Good luck! PS: I don't think it's too much of a problem (only in summer) mine has been doing it for years and I thought that was the norm.

plumb1_2 · 14 October 2004 at 1:52AM

I have this problem too. A couple of suggestions: (1) on the side of the pump (mine, anyway) is a black switch with 3 settings on it. I turned mine down to 2 which eliminates one radiator coming on. (2) phone round your local plumbing suppliers and get quotes for the part you need, you'll be surprised. That way you only have to pay for the work. Good luck! PS: I don't think it's too much of a problem (only in summer) mine has been doing it for years and I thought that was the norm.

You,ll have us going broke ;D ;D ;D ;D ;D ;D ;D ;D ;D

welshblob · 27 October 2004 at 9:13PM

Hi,
I've just moved and I had a similar problem with my heating system, a couple of the radiators coming on when heating the water. My house is only 7 years old so thought it would be a bit odd for the motorised actuator or valve to have gone so I had a look. I have a Danfoss HSA3 actuator which has a switch on it to allow you select between Manual or Auto, it was switched to Manual. I believe this opens the value allowing the system to be drained. Switching it to Auto seems to have solved my problem.
Cheers
Rob

Two Radiators on when Hot Water on but Heating off

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