Why is my boiler on...when it should be off?

Why is my boiler on...when it should be off?

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Discussion

essayer

9,082 posts

195 months

Tuesday 7th January 2014
quotequote all
Some bodged boiler installs may take creative interpretations of the component ordering smile

Like, mine when I moved in, which used one live feed to move the zone valve AND switch on the boiler / pump..

Tiggsy

Original Poster:

10,261 posts

253 months

Tuesday 7th January 2014
quotequote all
more clues.....the boiler is not on right now.....and the timer is OFF for heat and water.

If I turn the boiler stat up from 5 to 6....the boiler comes on!!!

So that tells me that the boiler is sending hot water to the tank 24/7 controlled only by the BOILER stat and ignoring the tank stat....right???

So - new valve needed. No gate valves either side of it - sods law.

Now...dumb question.....why is there only one valve? what about the radiators? where does that water come from???? I assumed one for water, one for rads???

Rickyy

6,618 posts

220 months

Tuesday 7th January 2014
quotequote all
Tiggsy said:
more clues.....the boiler is not on right now.....and the timer is OFF for heat and water.

If I turn the boiler stat up from 5 to 6....the boiler comes on!!!

So that tells me that the boiler is sending hot water to the tank 24/7 controlled only by the BOILER stat and ignoring the tank stat....right???

So - new valve needed. No gate valves either side of it - sods law.

Now...dumb question.....why is there only one valve? what about the radiators? where does that water come from???? I assumed one for water, one for rads???
Do you have a three port valve or two-two port valves?

They work slightly differently.

With a two port set up, it works as follows:

Hot water is selected, this sends power to the cylinder stat, if the cylinder stat is calling for heat. it sends power to the brown wire on the two port. This operates the motor, which opens the valve and also operates a micro switch. This micro switch has a permanent live supply on one side (grey wire) and the other side gets wired to the boilers switched live (orange wire). The microswitch is what fires the boiler. All the timer does is eventually open the valve.

When the demand is over, the valve is sprung return to the closed position, releasing the micro switch. If the valve is stuck, it won't return and the switch stays in the "on" position. The boiler will fire continuously until the water inside the primary circuit (not the cylinder) reaches the temperature set on the boiler's control stat.

Three port valves are different. Most rest in the HW only position when there is now power. Demanding HW will power the cylinder stat. The "demand for heat" wire from the cylinder stat is wired direct to the boiler switched live, the valve does nothing.

When heating is selected, the white wire is powered, which moves the valve into the mid position.

When heating is selected and how water is off/satisfied, the grey wire and white wire are powered and the valve moves to the heating only position.

If it is a three port valve, its possible that the microswitches are buggered. If that is the case you could probably get away with changing just the actuator head.


Tiggsy

Original Poster:

10,261 posts

253 months

Tuesday 7th January 2014
quotequote all
is that DIY?

Rickyy

6,618 posts

220 months

Tuesday 7th January 2014
quotequote all
Depends how handy you are with electrickery.

Usually just a case of removing a few screws and changing a few (like for like) wires. Be warned, not all models of zone/three port valves have removable actuators.

If its a Honeywell with an orange section between the actuator and brass body, its not removable and you will get wet if you try!

Tiggsy

Original Poster:

10,261 posts

253 months

Tuesday 7th January 2014
quotequote all
Rickyy said:
Depends how handy you are with electrickery.

Usually just a case of removing a few screws and changing a few (like for like) wires. Be warned, not all models of zone/three port valves have removable actuators.

If its a Honeywell with an orange section between the actuator and brass body, its not removable and you will get wet if you try!
well my dad is a (retired) spark so might have to drag him over!

How would I know if its that or the whole valve thats buggered?

Rickyy

6,618 posts

220 months

Tuesday 7th January 2014
quotequote all
Best thing to do is to buy the entire valve, which usually works out just slightly more expensive than buying just the actuator, replace the actuator first, if no joy replace the valve too.

I don't think you can buy just the valve body. Can you find out what model it is? I may have a few spare actuator heads kicking about in the garage.

Brother D

3,727 posts

177 months

Tuesday 7th January 2014
quotequote all
I have exactly this issue at the moment and new actuator head sat next to me, except the microswitch was stuck and the valve closed, resulting in the boiler boiling water and banging...

I think one of the earlier posters mentioned drayton - and I have previously had this issue with a Drayton, and I probably should try another valve rather than like for like which are appearing to be unreliable... Recommendations? - I stuck with drayton as I can just swap the actuator in a few mins

Tiggsy

Original Poster:

10,261 posts

253 months

Tuesday 7th January 2014
quotequote all
does this help?






Busterbulldog

670 posts

132 months

Tuesday 7th January 2014
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About time..just replace the synchron motor..the silver round bit with 2 wires..

Tiggsy

Original Poster:

10,261 posts

253 months

Tuesday 7th January 2014
quotequote all
ok...that wont leak water everywhere?!!!

and how do I find the honeywell motor to suit that valve?

Busterbulldog

670 posts

132 months

Tuesday 7th January 2014
quotequote all
Go to any plumbers spares place eg Plumb centre ,ask for a replacement synchron motor or

http://www.ebay.co.uk/itm/SYNCHRON-MOTOR-UNIVERSAL...

Tiggsy

Original Poster:

10,261 posts

253 months

Tuesday 7th January 2014
quotequote all
sorted!

Last daft question...if this valve is bust open.....why do my rads work as they should? (not that it matters...they work! Just curious!)

Busterbulldog

670 posts

132 months

Tuesday 7th January 2014
quotequote all
The motors burn out its the most common fault on these valves..occasionally the microswitches break..you could replace the whole valve there should be gate valves to allow isolation

Rickyy

6,618 posts

220 months

Tuesday 7th January 2014
quotequote all
The motor in that has been replaced before. It may not be the motor that is fubared. Hard to tell from the angle whether the head is detachable or not. Need a side on view to be sure.

Detachable heads should have a bump on the the silver case (which isn't shown in your pics). You should also see a gap between the actuator head and the brass valve body, there will be two screws holding the head to the body.

Non-detachable heads have an orange gasket between the head and body and are held down by four screws.

Tiggsy

Original Poster:

10,261 posts

253 months

Wednesday 8th January 2014
quotequote all
ok...the head is detachable...but going to try the motor first.

here's an oddity.....i switched the boiler off at the plug all night. so it didnt fire.

9am this morning and the hot tank is still too hot to touch...immersion is NOT on. Residual heat or aliens????

Tiggsy

Original Poster:

10,261 posts

253 months

Wednesday 8th January 2014
quotequote all
Fixed it!!!!


New motor, £18 - all works fine!

And a new jacket for the tank.

I suppose having an un-jacketed hot tank kept at the max temp of the boiler stat 24/7 for the last 6 months is why a) my airing cupboard was always hot and b) my gas bill so high!

Busterbulldog

670 posts

132 months

Wednesday 8th January 2014
quotequote all
Well done smile

Tiggsy

Original Poster:

10,261 posts

253 months

Wednesday 8th January 2014
quotequote all
Feeling quite pleased with myself!

Busterbulldog

670 posts

132 months

Wednesday 8th January 2014
quotequote all
Well so you should be you have saved yourself a few bob and learned something too