British Gas UP2 failing to turn on Central Heating except when Hot Water is on

[phatado]

OK, so I'm not a plumber but have a fairly good idea how this system works. I'm not alone with this problem either, there has been a similar post but it's old and doesn't have a resolution - though they have a temporary fix that doesn't work for me...

Boiler: Baxi Solo 15HE
Controller: BG UP2
Wireless Remote: WR1
Mid Position Actuator: BGMVSP-23
Room Thermostat: t4RF
Tank Thermometer: LP1


So basically I have had the system for over 3 years without a problem. Last week I fired up the Central Heating to test it out and perfect, no problems.

Yesterday however when I went to put the Central Heating on, it wouldn't come on. It's set to come on, the room thermostat is up enough to come on, the wireless receiver has the green light to say come on but it's not on.

The hot water works fine (and again today) so the boiler itself works fine.

Then I noticed if I turned on the HW AND the CH then they both worked together - meaning the Mid Position Actuator can route the water to the central heating.

I found the following link about a similar problem (http://www.electriciansforums.co.uk...s/55870-strange-fault-drayton-programmer.html) - however they could rectify this (temporarily) by removing the controller and putting it back or with a new one. However this does not work for me. I have removed the controller several times - pushed the contacts close together so they made contacts with the pins and turned the power off both to the controller and to the whole system, boiler and all at the house fusebox.

I did notice yesterday that when I turned the power back on, the CH was still set to come on, and when the wireless receiver received the message to heat up it:
1. Tuned the light green
2. The Mid Position Actuator moved to the position it should be when just the CH should be on.
3. When I turn the HW on the valve moves back to the middle and both the HW and CH come on.
4. Turning the HW off again the CH goes off again
5. The Mid Position Actuator does not move back up.

So this is a new problem to me and people have had similar problems. I don't think it's wiring as none are loose.

Could it be the controller or a valve somewhere? Any ideas appreciated!

I'd call British Gas but don't have a great hope in their 'experts'.

I have a baby on the way any day now and so could do with some heating!!!

 

[Darkwood]

Welcome to the Forum, maybe a tad late for replies on this but do check back in tommorow.

 

[davesparks]

I would suspect the valve based on what you have said, but would want to confirm by testing it before giving a definate answer.

If the valve is moving to all the correct positions for the various combinations of demands but the boiler doesn't fire on CH then it's likely one of the micro switches in the valve head has stopped working.

 

[phatado]

I would suspect the valve based on what you have said, but would want to confirm by testing it before giving a definate answer.

If the valve is moving to all the correct positions for the various combinations of demands but the boiler doesn't fire on CH then it's likely one of the micro switches in the valve head has stopped working.

Hi, thanks for the super quick reply! As I said I don't know lots about this system - however one thing about your reply is that once I have the HW and CH on at the same time and they are pumping away, if I turn off the HW the valve doesn't change position then. That would strike me as though the signal isn't getting to the valve to say "change to just CH".

Only when I power off and the valve goes to the default position and turn on and hit CH on does the valve move to the CH position, but the CH still does not turn on....

Again, I don't know much about the inner workings of these things...

 

[Leesparkykent]

Or the cylinder stat is stuffed!

 

[phatado]

Or the cylinder stat is stuffed!

Really don't think it's the cylinder stat. In fact that's one issue with the CH coming on with the HW, once the HW cylinder gets up to temperature, it shuts off the HW and then the CH stops.

I can stop and start it again by turning the HW thermostat up and down again - but ultimately I don't want to bring it up above 60 degrees C...

 

[davesparks]

Hi, thanks for the super quick reply! As I said I don't know lots about this system - however one thing about your reply is that once I have the HW and CH on at the same time and they are pumping away, if I turn off the HW the valve doesn't change position then. That would strike me as though the signal isn't getting to the valve to say "change to just CH".

Only when I power off and the valve goes to the default position and turn on and hit CH on does the valve move to the CH position, but the CH still does not turn on....

Again, I don't know much about the inner workings of these things...

Sounds like it could be cylinder stat then.

 

[Leesparkykent]

I would bet it's the cylinder stat :icon12:

 

[phatado]

Ok, I'm perplexed...

As I see it the one thing that seems to be working for sure if the cylinder stat.

The HW works fine - gets the tank up to temperature and then turns off.

If I turn the HW and CH on together then fine, both work (as long as the cylinder isn't up to temperature). If I turn the HW off whilst both are on then the pump stops pumping and the boiler goes off - i.e. the CH stops. ALSO the valve does not switch to CH mode - it stays in the dual mode.

If the CH and HW are on together and the cylinder gets up to temp then the HW goes off (as it should), but also as above - the CH stops and the valve doesn't move to the CH only position. I can then turn the HW back on by increasing the temperature on the cylinder stat (which turns the CH on) and turn it back off by changing the temperatue back down on the cylinder stat.

So as I said - to me that's one bit that's working fine.

I added a link to a previous thread in my first post and the person had a similar problem they could fix temporarily by removing and replaceing the UP2 control. This doesn't work for me. I did private message them and they have messaged me back to say that they eventually fixed their problem, after 8 visits by BG, by buying a Seimens controller that fit directly onto his back plate. He did say to manually try move my valve first in case it's not making it all the way - so will try that first...

 

[phatado]

What's the reasoning you have behind this conclusion? Really no idea where you draw this conclusion - though as I've stated several times, I'm no expert on this - just a DIYer...

So curious why 2 of you think this...

 

[Leesparkykent]

What's the reasoning you have behind this conclusion? Really no idea where you draw this conclusion - though as I've stated several times, I'm no expert on this - just a DIYer...

So curious why 2 of you think this...

when the hot water is satisfied the normally open contact is not closing. The normally open contact on the cylinder stat is connected with the grey on the valve and the hot water off terminal on the programmer.

 

[davesparks]

What happens with DHW off at the programmer? Does the CH then work?

For the valve to move to the CH only position it needs a CH 'on' signal from the room thermostat AND a DHW 'off' signal from either the programmer or cylinder stat.

The BG UP2 programmer is just a rebadged Drayton LP722.

 

[phatado]

What happens with DHW off at the programmer? Does the CH then work?

For the valve to move to the CH only position it needs a CH 'on' signal from the room thermostat AND a DHW 'off' signal from either the programmer or cylinder stat.

So I have noticed that it's slightly different to how I described before:

1. If I turn on just HW then the valve moves to just HW I get just HW and it heats the cylinder.
2. If I turn on just CH the valve DOES move to the CH position, but even if the the room thermostat is set above the room temperature the CH DOES NOTcome on.

Strangely - if I am in scenario 2 above - with the CH switched on and the valve in the CH position, if I turn the HW on as well then the pump kicks in and the boiler starts up - the weird thing is the valve does not move into the middle, dual CH and HW position - it stays at the CH position and the rads heat up. This does not seem to heat up the cylinder (which is fair enough as the valve position is in CH only for some reason).

In the above scenario, once the room comes up to temperature the signal goes to the controller to turn the CH off (obviously the CH light is still on in the controller as the timer is on CH) - it's just got the signal to stop as the temperature is up. When this happens the valve moves to HW only and then it heats just the cylinder.

If I then put the room thermometer back up it moves into the dual position and heats both.

So I still have the same problem of the CH not coming on by itself...

So to me the really weird thing is:

1. The CH not coming on by itself, yet the valve is moving into position and so thinks it should come on.

2. If the CH is supposed to come on and the controller has a green light and the valve is in the CH position - if I then ALSO then put the HW on, both lights on the controller are on, but the valve does not move to the dual position and stays in the CH position heating just the rads.

 

[phatado]

when the hot water is satisfied the normally open contact is not closing. The normally open contact on the cylinder stat is connected with the grey on the valve and the hot water off terminal on the programmer.

Hi,

Sorry, again I'm not quite sure why you think this points to the cylinder stat- how would this affect things when I have just CH set to come on which doesn't work - despite the valve moving into the CH place.

As I said, if I then turn on the HW and the temperature is below the cylinder stat setting, then the CH comes on. As i have just said in the above reply, the odd thing is that the valve stays in CH position in this case and only the rads heat up, despite both the CH and HW being on...

 

[davesparks]

An electrician could have found the problem within a quarter of an hour, yet you prefer to spend days with a broken heating system to come on here for our best guesses?