Diverter valve issues help required.

[kman]

Hi i'm hoping someone may be able to offer some advice. I
replaced a diverter valve motor on my hot water/ central heating system. I’d been meaning to do for some time, up until now I’d been manually sliding it with the level to get HW, CH or both and this worked just fine. Now as far as I can tell the motor is moving fine when set to CH the valve opens and water is directed downwards into the heating system and the radiators get hot as normal exactly the same as what I’d been doing by hand. However I can’t seem to get hot water now it’s only luke warm regardless of wether I have CH, HW or both sleected.

Q1) Is it possible that the valve is getting stuck in some midflow position? When installing the motor I wasn't sure whether I should have latched the valve fully open? I did not do this. I'm not sure if this makes a difference to the mechanism.

Q2) Can anyone tell me what the big red tap does? Playing with that has temporarily giving some piping hot water. Any ideas?

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• kman
• 31 Mar 2008
• 2

 

[kevplumb]

bypass

 

[kman]

bypass

Correct me if wrong but normally I would want this closed?

 

[kevplumb]

Correct me if wrong

you are

but normally I would want this closed?

no

it should be set to give the minimum flowrate through the boiler

 

[Rob]

Dont really need a bypass on a Y plan.

 

[kman]

Dont really need a bypass on a Y plan.

How do you set the bypass valve correctly what is the procedure? Any comments about the installation menthod of the diverter valve motor?
Thanks.

 

[Agile]

This looks as if its a heat store?

If so then it may have a blending valve on the HW output. If so then that may have failed.

If its not a heat store then it may be an unvented and if thats the case it might not have the correct safety devices fitted.

The bypass red tap should be able to be closed from what we can see in your picture. The whole of the cylinder would have been more helpful though!

Tony

Tony

 

[kman]

Top half, there is only one pipe as you can see. It a cold feed, perhaps directly from the mains? There is no other tank in the house. I’m wondering what the dome thing is on the right, earlier pictures? I know the lower box is the thermo couple. Does HW come straight out of the store or is it blended with cold?

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• kman
• 31 Mar 2008
• 1

 

[Agile]

I know the lower box is the thermo couple. Does HW come straight out of the store or is it blended with cold?

What you know is not the same as what I know!!! Its actually a shock arrester!

You have a thermal store. These are not everyones preference but were popular with estate builders during the 80s.

Behind the shock arrester is what I expect is the blending valve. taht has probably failed or become seized up.

If you take a close up of it and repeat any type numbers we may be able to give you more advice.

Also take hot water and see if one pipe to it is a lot hotter than the output pipe.

Tony

 

[kman]

What I can read off this component is as follows;
Zilmet model z50
total capacity 0.5l
preloading pressure 3.5bar
expansional vessel, max working pressure 10bar, testing pressure 15bar,

 

[tonybhoy]

Think he was talking about the blending valve mate not the shock arrester .

The blending valve is right behind the shock arrester,it's a brass three way valve.

 

[kman]

I've been monitoring the system for a few days. I did an experiemnt I set the timer on an to HW only. After 30minute everything was fine and nice hot water at the taps. I then set the timer to HW+CH and immediately the HW ouput from the tank store goes stone cold. The CH heating warms up I let the system reach an equilibrium such that the boiler is off beacuse everything has reached thermostat temp. All rads hot but still no hot water, bareley luke warm even though the store inlet HW pipe and CH pipe feed are piping hot. I've tried manually sliding the diverter valve but its already in the correct position.I'm a bit lost could this be an internal tank problem?

 

[Agile]

I would suggest that the heating coil of the store is somewhat blocked and will work if the heating is off but the flow reduces too much when the heating is on.

You would need to monitor the temperature of each end of the heating coil in each of the programming positions.

Rebalancing the rads with the lockshields starting at only 1/2 turn open might help.

Tony

 

[kman]

I would suggest that the heating coil of the store is somewhat blocked and will work if the heating is off but the flow reduces too much when the heating is on.

You would need to monitor the temperature of each end of the heating coil in each of the programming positions.

Rebalancing the rads with the lockshields starting at only 1/2 turn open might help.

Tony

What's the ultimate solution to this, new tank?

 

[kman]

Just a thought but does this look like a store as opposed to just a simple tank? If's it's a store where is the heat exchanger, would it be inside the tank?