Central heating manifold puzzle

[stevenabell]

Hello all,

Hopefully this is child's play for some bright spark.

This is the situation:
Baxi Potterton boiler, central heating enabled on boiler, underfloor heating, thermostats in individual rooms cranked right up, heating does not work in any room.

The problem:
Hot water appears to be reaching the manifold. The areas indicated in red in the picture below reflect those which are very hot to touch:

http://www.eurochangecharity.org/manifold.jpg

The plastic tubes directly beneath each valve feel cool to touch, though I do not know whether this is by design or not. The tubes in the upper part of the picture disappear down into the floor, and directly in front of where they do, their sister tubes emerge back up from the floor and are shown in the lower set which are coloured in red/blue accordingly. Needless to say the pipes going into the manifold and coming back out of the manifold into the boiler are also very hot to touch, though I did not show this in the picture.

So - can anyone tell me what might be happening? If it helps with the answer, I haven't had the heating switched on for over 12 months. I first thought of blocked pipes - but surely not in all 6 rooms? Too much of a co-incidence, hence my suspicion over something to do with the manifold.

Any pointers greatly appreciated,
Steve[/img]

 

[Gasguru]

The item to the left of the pump would normally be a thermostatic mixing valve...although it looks a little odd. If the head unclips check the actuating pin has not stuck down.

 

[stevenabell]

Many thanks for the super quick reply; sincerely appreciated.

I've taken a closer look at that valve, a picture of which is here (minus its sheath) :

http://www.eurochangecharity.org/mix-valve.jpg

The apparent dial inside looks like it may want to turn, but attempting to do so (it's very stiff) only yields about 3mm anticlockwise. Given that the pipes either side of this valve are hot to touch, I just assumed that it was getting through this piece okay?

Perhaps worthy of note are the dials located beneath each "tap" :

http://www.eurochangecharity.org/dial.jpg

For those which turn (albeit only slightly), this does not seem to make any difference.

Does this help any?

Thanks again,
Steve

 

[gasanstuff]

CHECK THAT THE PUMP IS ACTUALLY WORKING

 

[stevenabell]

I _assume_ that the pump is working, given that the pipes either side of it are hot to touch? If it were not fully functional, I would expect the pipe between the pump and the actual manifold to be cold. Of course it's possible that I'm missing something because I know very little about these things.

Thanks,
Steve

 

[gasanstuff]

does the pump make a noise? remove central screw you can see if it spins. test for 240v if you are able to

 

[heatingman]

from looking at the pictures it looks like the actuator heads are opening, pop one off and check the pin moves. Remove centre chrome screw from pump and confirm the motor is turning, make sure the return balance valve is not jammed. How cold is it in your house?.
Might need to remove pump head and check rotor is still in place and housing isn't full off crud.

 

[stevenabell]

The pump is making a noise. Or, at least it WAS. I managed to unscrew one of the actuator heads (the one for the kitchen) until it popped off, exposing the pin beneath. The pin does press down if I apply enough pressure, and pops back up to its natural position. Now, it was just around this time when:

- the pump stopped making a noise

- the plastic tube directly beneath the actuator head started to get warm

- the lower set of actuator heads and valves have now gotten cooler.

BUT... still no heating in the kitchen and I've left it a good 20 mins or so. Perhaps tellingly, although the boiler is activated for central heating, the burner is not lit which tells me either that the manifold is not calling for hot water, or the water in the pipes has reached temperature.

I haven't yet unscrewed the screw in the middle of the pump (it's extremely hot, by the way!) And to answer a previous question, the flat is about 15 degrees C.

Does this shed any more light?

Really appreciating your willingness to help - absolutely superb stuff.
Steve

 

[Norcon]

Check the pump rotor as already stated by others.
If it hasn't been operating for a while than it will likely be jammed.
More elaborate UF controllers exercise the UF pump periodically when shut down.


The manifold will heat up any way when UF pump OFF with a TMV system due to the primary pump operation and zone valves open.
A back flow can usually occur on the by-pass branch also.

 

[heatingman]

with the weather we have at the moment you will have to wait a lot longer than 20 mins before you notice any heat, especially if its been off for a long while. If its a screed floor it'll suck up heat for ages before you get any benefit. If the return plastic has gone cold it does indicate some water movement.

 

[stevenabell]

Thanks heatingman, I understand. I guess what confuses me is that the burner is not lit on the boiler. I'd expect it to be lit until the temperature on the thermostat in the individual room has been reached. I'll make an attempt to unscrew the screw from the middle of the pump and see if there's any movement in there.

 

[Agile]

Please pause to try to understand that the boiler will only light up if there is somewhere for the heat to go to !

We have told you many times that your pump is not pumping the water round the system.

Instead you fiddle with the TRVs, look at valves, look at the boiler not firing up.

How many times do you need to be told?

The pump is not pumping! As its not been used for 12 months thats only to be expected!

Tony

 

[Agile]

I _assume_ that the pump is working, given that the pipes either side of it are hot to touch? If it were not fully functional, I would expect the pipe between the pump and the actual manifold to be cold.

Thanks,

Steve

What you assume and what you expect are not relevant.

What is relevant is what the pros are telling you.