radiators hot when HW only selected

14 Nov 2003
Reaction score
United Kingdom
Hi All,

I wonder if anybody can give me any pointers on this problem. It started off in the summer when I had the programmer on HW only. I put my hand on one of the downstairs rads and it was hot! The room stat is turned totally down as well.

The motorized valve seems to work O.K, I can see that the lever on it moves to HW when only HW selected, CH when only CH selected and mid-position when both HW and CH required.

thanks in advance for any ideas.

BTW It is a Potterton Statesman boiler fully pumped/sealed system with Siemens Programmer, Room Thermostat, 3 way MV
Sponsored Links
The lever might be in the right position for hot water, but when it is, does the CH pipe from it get hot?
Hi Oilman,

yes all the pipes around the motorized valves are hot (very) and the room thermostat is off.

BTW I changed the motor part of the MV today but nothing different.

Is it possible for the manual overide to be in the wrong position? Would this give this result + if so how do I move it to try the other setting? i.e does the power have to be off or can it be moved with the power on? It is situated in a very tight location and I can't see the writing where the manual lever is.

I only moved into this property this year so I don't know any history

Take its head off, and move it with a pair of pliers or a small adjustable to one position then the other. Doesn't matter what's selected. It sounds like it may be the valve body.
Sponsored Links
thanks again Oilman

Err just to confirm....sorry I am a bit confused

take off the Motorized valves motor, move the manual lever to other position and then refit the motor head?

"Sounds like the valves body" Do you think then that the motor is working but the valve body is stuck in the both HW and CH position.

Take the head off, leave it in auto and select HW or CH and then move the spindle that sticks out of the valve body. It won't move far in each direction.

I don't think the valve is stuck, I think it leaks to both sides at once.
O.K I understand now

I will give that a go tomorrow morning, will let you know what happens.

thanks again Oilman!
What make valve is it? If it's Honeywell it is likely to "let by" with the head off - the spring return in the head pushes the rubber ball against the CH opening. They do seem to vary a bit.

I have taken the head off again, there is no spindle on the valve (it is in the head) The valve has a spring loaded toothed arm which I can move quite easily. I think it's gonna be a new motorized valve job!


Its a Siemens/Landis&Staefa 3 way model no.MAV322C

Very odd, I can't find anything about the valve on the landis site.

Are we talking about the same bits? It looks to me as if you have the cover to the head off with the head still on the valve body. I might be wrong as I don't know these valves.
I see why I couldn't find it, I put in MAV322C it's a MA-V322C. Even so, I can't see much as their site is one of these gimmick ridden bits of code which operate ok with microsnot and windoze, but not with anything else, so the page alternates from part blank to total blank over a 30 second cycle time. Never mind I will cross their products off my list of things to use. Sorry I can't help further.
O.K Oilman thanks anyway

I appreciate the time that you have put into this topic.....

and may I add that this is a great site and is firmly lodged in my favourites (oops Microsoft!)

I have found a technical helpdesk no. for Landis&Stuff and will try ringing them Monday


DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Sponsored Links