Honeywell System Issue

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Gavin Jones

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Hi,

We have recently moved house and now the weather has gotten colder, we are using the central heating a lot more.

We are finding that the Honeywell DT92E wireless thermostat is showing the room temperature as 23.5 degrees even though we have the desired room temperature as 19.5.

I have tried to re-pair the thermostat which hasnt made a difference.

The Water is set to All Day and the heating Auto so I wondered if the issue was actually with the diverter or something else you might be able to advise on?

The boiler was replaced a couple of years ago..

Thank you for your help..
 
Is the diverter that you refer to really a 3-port valve?

Turn the power off to the heating system. Does the valve return to its rest position? Does the operation of the manual lever meet with resistance, and can you hear the valve resturning to its rest position when you let go of this lever?
 
IMG_4646.jpg

This is what we have, there wasn't any resistance moving the leaver up and down and it definitely didn't return on its own but on diverter valves ive seen before they have a W, M and H but this just has Auto and Man

It looks the same as this:

https://cdn.plumbnation.co.uk/site/...ll-v4044c-1288-22mm-3-port-diverter-valve.jpg
 
Last edited by a moderator:
MeldrewsMate said:
Is the diverter that you refer to really a 3-port valve?

Turn the power off to the heating system. Does the valve return to its rest position? Does the operation of the manual lever meet with resistance, and can you hear the valve returning to its rest position when you let go of this lever?
Click to expand...

I went upstairs to have a look at turning off the power but the cable went into the loft so tomorrow morning ill turn power off and check the resistance etc as suggested
 
Gavin Jones said:
Ah, the post is waiting for moderator approval, this is it again..
Click to expand...
What i said in the other post waiting for approval was that there wasn't any resistance moving the leaver up and down and it definitely didn't return on its own but on diverter valves ive seen before they have a W, M and H but this just has Auto and Man

i wasnt able to turn the power off so will do that in the morning.

Thank you for the help so far..
 
It’s not a diverter valve it’s a 3 port mid position valve, same as the Drayton’s you’ve seen with W M H.
 
Gavin Jones said:
What i said in the other post waiting for approval was that there wasn't any resistance moving the leaver up and down and it definitely didn't return on its own...
Click to expand...
Then the valve may be seized in the open (or heating) position.
Depending on how competant you are with a screwdriver and a small spanner you can be coached to free it off, with the power off!
The sequence is:- Power off, Lid off, undo the (correct) two screws and remove the actuator, wiggle the valve shaft until it feels much more loose (easy to move 60° or so), replace actuator, replace lid, switch on power and test.
 
The three position valve default is domestic hot water (DHW) but the tank thermostat would need to be on to get the boiler to run, the valve internal wiring is like this
mid-position-valve.jpg
Orange to boiler, Grey live when DHW satisfied, and White live when Central Heating (CH) called for. The SW1 activates in mid position and the SW2 once motor fully over.

So if no DHW is required then white and grey are live, white takes it half way then grey takes it whole way across. But if DHW is required grey is not powered so it only goes half way across the diode give it around half power.

So for it to get hotter than thermostat setting, not only must the valve be stuck, but also the DHW must be cold, or there will be no power on orange to run boiler, at this time of year to use enough DHW for the central heating to run enough to over heat is unlikely, with only grey powered it may move valve if the switch sticks, but there would be no power out on the orange to run boiler.

However in winter with the DHW satisfied, then the valve will stick all the way across, as grey is powered, and will only return to default DHW once the DHW calls for heat again, this is normal, although valve held open the boiler is not running, so radiators should not get hot.

The Y Plan
Y-Plan.jpg
has a DHW off supply either from programmer or from tank thermostat.

Some times the micro switches stick, and this can result in no central heating, as a temporary fix some times people latch the bleed lever on, and this can mean in summer every time DHW is called for you get the radiators slightly warm.

I remember the old Y Plan as when grand children were babies it failed in daughters house, those resistors resulted in my getting some very odd test results, and I did not have the diagram I have just put up of inside the valve, what had happened was before my daughter bought the house it had gone faulty and the bleed lever had been latched on to keep it running, then my son-in-law cleaned the airing cupboard and knocked the lever unlatching it. So central heating stopped working.
 
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