Hot water regulation problem

[955Hugh]

Dear All,

I have a problem with regulation of our hot water supply. The boiler is a Remeha Avanta Plus and the heating control system is Honeywell.

The boiler is working and will fire when a heating thermostat is turned up, however the regulation of the hot water is not responding when we use hot water. The hot water tank becomes depleted and the boiler remains in standby during the on programme of the Honeywell. The boiler remains in standby even if the Honeywell continuous mode is selected for the hot water.

The problem has only manifested since the heating has been switch on after the summer; possibly just a coincidence! There are no error messages displayed on the boiler and restarting the system makes no difference.

I’m assuming it’s a hot water thermostat or sticking valve problem but I’m in no way qualified and only guessing! Any suggestions much appreciated.

Best Regards

Hugh

 

[Dotty]

Welcome to the forums Hugh. What temp is your stat set at? Start simply first!

 

[955Hugh]

Hi Thanks for the reply. The hot water temp (as set in the boiler programme) is at 60 degrees

 

[kay-jay]

Ok try this locate the hot water two port valve and manually move over the lever does the boiler fire now? (make sure there is hw demand)

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[955Hugh]

Thanks Kay-Jay, I did try this a couple of days ago and it seemed to work, i.e. hot water started to flow though the pipes to the tank when I moved the valve from auto to constant. I can't say if it fired the boiler as it was already being used by the central heating! I'll disable the central heating and try it again. Cheers Hugh

 

[kay-jay]

That's right mate turn off heating turn on water demand and manually open valve if boiler fires it will be a fault on the valve. If this is the case remove the head and try turning the spindle if it moves freely then you can just change the synchron motor

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[955Hugh]

Thanks Kay-Jay, I'll try the above. One question, the valve lever sometimes has resistance when I move it from auto to manual/open and sometimes is very slack. Is this usual? The overall problem seem to be Intermittent, i.e. the boiler is now firing and heating the hot water (central heating is off) and the hot water valve is in the auto position; it's as though it is sticking!

 

[kay-jay]

Sounds like the valve itself is sticking and may need changing in its entirety.

Unless....

Are all conditions the same when lever is moved? Or is it possible that the slack lever is present when demand is on? This could account for less resistance



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[snowhead]

Or is it possible that the slack lever is present when demand is on? This could account for less resistance
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Or has greater resistance when demand is on if the valve is fighting against the pump flow to open because the heating is on.

The valve actuator will show Auto whether the valve is open or closed in Auto.
Auto just disables the lever.

 

[955Hugh]

it seems it's a slack lever when the demand is on. When I switch the hot water demand off I hear the valve turn and the lever then has more resistance.

 

[snowhead]

Forget what I said about resistance then.

 

[955Hugh]

Seem to be getting somewhere! The boiler now fires when the demand is turned on (i.e. switch the Honeywell controller to continuous to override the auto programme setting, which is off at this time of day). The valve lever goes from resistance to no resistance (i.e. valve is open) and the pipes get warm, all seems to be working as it should; however it is intermittent and will probably play-up again if it is left for a few hours! Any ideas? Faulty (sticking valve), controller to thermostat not communicating? Cheers Hugh

 

[snowhead]

Most likely valve actuator head playing up, they can normally be changed without removing the valve.

 

[955Hugh]

cheers snowhead, I'll look to do that if it continues.