Radiators getting hot when only HW switched on.

[HFP]

Hi all, I hope you can help - I have googled, checked the Wiki and searched and not found an answer to this so apologies if it is a repeat that someone else has asked and you've answered.

I have a gravity fed water system, the gas boiler has a water pump fitted in with the system. I believe the system to be in the region of 18 years old. I noticed about a month ago that even with the central heating switched off the radiators where still getting up to full temperature whilst the hot water was set to on. Both the upstairs and downstairs radiators getting up to full temperature. How long this has been the case I couldn't say as the CH&HW were both on the same settings throughout the winter.

The gas boiler is an Ideal Excel
It is controlled by a Towerchron timer

The biggest clue I have from reading up is that the three way valve next to the hot water cylinder might be the culprit. This is a Honeywell F5 - 9628. I say clue, the lever on it whilst set to auto has no resistance to it when moved to manual and back again.

Could this be the cause or could it be a sympton of a dodgy electrical signal being sent to it? Is there any way I can check?

Many thanks in advance
Hugh

 

[D_Hailsham]

The biggest clue I have from reading up is that the three way valve next to the hot water cylinder might be the culprit. This is a Honeywell F5 - 9628. I say clue, the lever on it whilst set to auto has no resistance to it when moved to manual and back again.

Don't recognize the valve model, the mid position valve is usually V4073. There are two types of 3-way valves so can you check for any other numbers and post them?

If there is no resistance on the lever the valve is probably stuck. Turn off the power to the central heating and check the lever again. If it is still loose, the valve is stuck; but, if there is resistance when you move the lever, the valve was being held open by the motor.

Unfortunately the valve type is needed before I can post further checking instructions

 

[HFP]

Hi,

I have had another look and there are some more details on the back, they are nearly impossible to see so I resorted to some creative photography! As you can see from the photos you are totally correct. With the timer switched to off the lever still has no resistance, once I can see how to isolate the power without turning the whole house off I'll give it a go.

Thanks
Hugh

 

[gavinda]

its most probalbe the rubber ball inside has swollen. the easy option is to replace the whole body, you should be able to get that from any merchant, just ask for honywell mid pos body in 22mm. you could however fir a little bit more(or less depending on how you look at it) just get a service kit for it and just replace the ball and plate. good lick

 

[ChrisR]

The wiring of these valves seems to defeat a lot of plumbers, and the valve can appear faulty when it's not. To confirm, you do have to kill the power. You'll have to eventually anyway!
Then you should feel a resistance and hear a noise when you push the lever from Auto to Man.
If the wiring's wrong the valve can be open when it shouldn't be, depending on the sequence of instructions it gets.

 

[gavinda]

seems though from the op's post that historically this wasnt a prob, and now it is. therfore the worn valve letby seems more an issue than wiring.

 

[HFP]

Hi all, thank your for your posts - it is very much appreciated.

seems though from the op's post that historically this wasnt a prob, and now it is. therfore the worn valve letby seems more an issue than wiring.

That is correct, it used to work fine. Thanks for the advice, I will give getting a replacement a go.

 

[HFP]

UPDATE

I bought a new valve off eBay for £36 delivered (£69 from Screwfix) and fitted it today. The old valve is totally jammed open hence the 'dual heating'. The new one works perfectly.

Many thanks to all who replied.