Lots of hot water but no central heating

[Wildeman]

Update to my issue:

Last night I turned off the system and boiler and then closed the valves at both ends of all the rad's. I then went round bleeding them all starting from the bottom of the house. There was air in all of them and I left the bleed nipple open and then opened the flow and let water run out for a minute or two and in most case there was air in with the water. I then closed the valve and bleed nipple and moved to the next rad.

I also bled the drain cock on the return back to the boiler and I also did this with the valve manually in the CH only position to make sure I go a flow (hoping this indicates no blockage! )

I then opened the TRV and lockshield valve on just one radiator upstairs as I am not sure which is the first rad in the circuit or the one closet to the boiler. I fired up the heating and removed the actuator and moved the valve manually to the CH only position. The boiler lit and after a few minutes it went out and no heat to the pipework in the airing cupboard. I moved the valve manually to the mid position there was air noises in the pump and pipework and heat, then after moving back and to from the mid position to the CH only position I got heat to the single rad.

I then tried to open the valves on another rad and this was hot but when trying to open a third one back to normal cooling pipes and boiler out. All the time I could hear air in the pipes especially around the pump.

I have the pump on number 1 to stop it drawing air into the system and the F&E tank is full of water.

Any further suggestions - I was planning on repeating the process again tonight of bleeding and then try again

 

[MANDATE]

Sounds like the resistance on heating side is too high.
When both HW and CH are operating it copes with it because the HW is taking the bigger share. When HW is satisfied the HW port closes and the CH port opens fully so all the flow is now directed to the radiators.
It could be all the lockshield valves are not open enough to allow the same amount of flow. If flow is restricted the boiler temperature will rise and boiler stat will operate.
I think its worth opening the lockshields more to test this out.

 

[Wildeman]

Sounds like the resistance on heating side is too high.
When both HW and CH are operating it copes with it because the HW is taking the bigger share. When HW is satisfied the HW port closes and the CH port opens fully so all the flow is now directed to the radiators.
It could be all the lockshield valves are not open enough to allow the same amount of flow. If flow is restricted the boiler temperature will rise and boiler stat will operate.
I think its worth opening the lockshields more to test this out.

Have tried that but the pipe work cools and the boiler goes out, move the valve manually back to mid position and the boiler lights instantly and not pipe work again, move the valve back to CH only and nothing!!!

 

[MANDATE]

As you know the flow from boiler goes to pump and then into 'pump' port on the valve and out through the 'HW' port.


Suppose the flow from boiler was in reverse order due to pump being wrong direction, so flow would be into 'HW' port and out through 'pump' port. This would have no adverse effect on HW.

If both HW and CH were selected and valve was in mid position, it still would have no adverse effect. flow into 'HW' port and out through both 'pump' and 'CH'

Now if only CH is selected the HW port is shut off so there can not be any flow into the valve, so temparture at boiler builds up till boiler stat stops it.

There will still be a path through valve 'pump' port to 'CH' port but it won't do much if the flow from boiler is into HW port. I think it would just circulate the existing warm water till boiler turns off.
Based on this I think its worth checking out

 

[Wildeman]

As you know the flow from boiler goes to pump and then into 'pump' port on the valve and out through the 'HW' port.


Suppose the flow from boiler was in reverse order due to pump being wrong direction, so flow would be into 'HW' port and out through 'pump' port. This would have no adverse effect on HW.

If both HW and CH were selected and valve was in mid position, it still would have no adverse effect. flow into 'HW' port and out through both 'pump' and 'CH'

Now if only CH is selected the HW port is shut off so there can not be any flow into the valve, so temparture at boiler builds up till boiler stat stops it.

There will still be a path through valve 'pump' port to 'CH' port but it won't do much if the flow from boiler is into HW port. I think it would just circulate the existing warm water till boiler turns off.
Based on this I think its worth checking out

Am at work at the moment but will check tonight but am sure the flow arrow on the pump casing is pointing down towards the valve. Could it be the wiring is causing the pump to spin backwards even though it is installed the right way around. (Live and Neutral crossed!!)

I can understand your theory and hope it is something simple like that!!!

 

[MANDATE]

As you know the flow from boiler goes to pump and then into 'pump' port on the valve and out through the 'HW' port.


Suppose the flow from boiler was in reverse order due to pump being wrong direction, so flow would be into 'HW' port and out through 'pump' port. This would have no adverse effect on HW.

If both HW and CH were selected and valve was in mid position, it still would have no adverse effect. flow into 'HW' port and out through both 'pump' and 'CH'

Now if only CH is selected the HW port is shut off so there can not be any flow into the valve, so temparture at boiler builds up till boiler stat stops it.

There will still be a path through valve 'pump' port to 'CH' port but it won't do much if the flow from boiler is into HW port. I think it would just circulate the existing warm water till boiler turns off.
Based on this I think its worth checking out

 

[Hugh Jaleak]

Swapped live/neutral on single phase electricity wont make the pump run backwards, so you can rule that out! Arrow on pump indicates direction of flow, so assuming that is pointing towards the valve then pump is unlikely to be the culprit.

 

[MANDATE]

Swapped live/neutral on single phase electricity wont make the pump run backwards, so you can rule that out! Arrow on pump indicates direction of flow, so assuming that is pointing towards the valve then pump is unlikely to be the culprit.

Agreed, unless the flow is going into the wrong 'port' on the valve

 

[Wildeman]

I have checked and the flow arrow on the body of the pump is pointing towards the valve so it is the right ways round and it is going I to port AB on the Sunvic valve which is the pump and the actuator is on the correct way around although I have proved it not to be the wiring as manually moving the valve proves this.

What next??

 

[Wildeman]

Another update - last night I had the floorboards up on the landing to check for hidden valves and as far as I can see there aren't any and the microbore does not come off a manifold as I orignally thought just reducers to 10mm

I was wondering whether the feed and expansion pipes or the pipe that joins then together before the pump maybe blocked so I put a pipe on the overflow and blow into it and bubbles came out of the feed pipe into the F&E tank and then I put the pipe onto the feed from the F&E tank and blew and water came out of the overflow - so I am presuming this means that the pipe work there is clear.

View media item 15492
As I say I have checked and the pump is the correct way around and I bleed the pump and water dribbed out. The pump is a Wilo Gold RS50 (is this big enough for the job) which I believe previous owners installed.

View media item 67193
I connected a pipe to the drain on the end of the return to the boiler and put the other end under water in a bucket and when I opened it there was a lot of air even after the air was expelled from the pipe.

View media item 15443
There still seems to be a lot of air in the pipes though passing around the pump and some in the the lower radiators. I have noticed that when in central heating only position after the initial heat from the boiler has gone the flow from the boiler pipe is cool and the return is red hot!!!! When in HW only or HW/CH then the flow is red hot and the return noticably cooler!!

What can I try next and does this help to indentify more about where or what the problem is?

 

[MANDATE]

Still trying to work out what could be causing your problem.
If you just put CH on and leave HW off, does the valve move through the mid position and forward to CH position and does the boiler and pump operate. (I think you've said it does,but boiler/pump stop after a couple of minutes) based on the above being correct I cannot see it being a wiring problem.
The pathway through the heating side is ok when both CH and HW are operating.
The pathway through the heating side is restricted/blocked when only CH is operating, this restriction/blockage causes the boiler to shut down.
So what's changed?
The HW port has been closed off and the CH port has been opened fully.(valve spindle in different position) (can spindle be incorrectly located)
The flow of water to CH side has increased (because there is now no flow to HW.)
The resistance in the CH side remains the same but when HW port was half open there was a escape route which of course is no longer there.
Question! Is there a 'by pass' pipe with valve on it which would run from between pump and valve to the 'return' side of boiler.
Have you tried running CH only with all valves fully open (including the lockshields.
Have you tried with actuator head off having the spindle in the CH position, but running the boiler on HW only and does this give exactly the same problem. (stops have couple of minutes) and if it does then just turning the spindle makes the difference.
I cant think of any other situations that would give those problems.
Question? Has this system ever worked correctly or is this a problem you've inherited.
Do let us know when you find the cause.

 

[MANDATE]

just noticed you had this problem back in 2009.
Did you carry out the test suggested by D Hailsham on Oct 14 2009

 

[Wildeman]

Still trying to work out what could be causing your problem.
If you just put CH on and leave HW off, does the valve move through the mid position and forward to CH position and does the boiler and pump operate. (I think you've said it does,but boiler/pump stop after a couple of minutes) based on the above being correct I cannot see it being a wiring problem.
The valve does move through the mid position to the far CH position and the pump and boiler light but the boiler goes out after a few minutes but the pump is running continuously

The pathway through the heating side is ok when both CH and HW are operating.
The pathway through the heating side is restricted/blocked when only CH is operating, this restriction/blockage causes the boiler to shut down.
So what's changed?
The HW port has been closed off and the CH port has been opened fully.(valve spindle in different position) (can spindle be incorrectly located)
The flow of water to CH side has increased (because there is now no flow to HW.)
The resistance in the CH side remains the same but when HW port was half open there was a escape route which of course is no longer there.
Question! Is there a 'by pass' pipe with valve on it which would run from between pump and valve to the 'return' side of boiler.
There is no bypass valve only a valve on the flow to the cylinder.

Have you tried running CH only with all valves fully open (including the lockshields.
Yes and still the same lack of heat

Have you tried with actuator head off having the spindle in the CH position, but running the boiler on HW only and does this give exactly the same problem. (stops have couple of minutes) and if it does then just turning the spindle makes the difference.
Correct - the minute I start to move the valve manually with the head off back towards the mid position the water runs red hot and the boiler lights!!

I cant think of any other situations that would give those problems.
Question? Has this system ever worked correctly or is this a problem you've inherited.
I am not 100% sure on this as the cylinder stat was always on max but now we have a new tap in the kitchen the water has to be at 65 and no hotter otherwise the valves in the tap will fail !!!

Do let us know when you find the cause.

 

[Wildeman]

just noticed you had this problem back in 2009.
Did you carry out the test suggested by D Hailsham on Oct 14 2009

Yes have had this problem for a while and cannot get a fix for it, I believe I did try the wiring changes temporarily as suggested by D Hallsham back in 2009 and think it made no difference and proved it not to be the wiring!

 

[picasso]

I havent read the whole thread but I would be looking at changing the pump.