Discuss My Central Heating Doesn't Work - Master Thread in the Plumbing Forum | Plumbing Advice area at PlumbersForums.net

Dan

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I thought I'd create a master thread to move all of these similar threads into, over time like.

  • If your central heating doesn't work
  • boiler doesn't work
  • radiators not working
  • radiators or heating system is cold
  • thermostat wont work or respond
Then post a reply in this thread. Rather than us creating 100's of threads with the same issue. (Where in most cases a Gas Engineer will probably need booking - so we'll then push the customer to the post a job area after their input in this thread.)
 
Main Combi 24 HE water heats up fine, Central heating does not.
I replaced the thermostat - nothing, I found a second hand pcb and it fired up the heating for 15 mins before switching off- not sure if the pcb is being fried or what else might be the problem ??
When the thermostat is calling for heat, NOTHING at all happens- no sounds of relays or pump running total silence- Does anybody any clues where to start looking for a fix please?
Many thanks
 
Main Combi 24 HE water heats up fine, Central heating does not.
I replaced the thermostat - nothing, I found a second hand pcb and it fired up the heating for 15 mins before switching off- not sure if the pcb is being fried or what else might be the problem ??
When the thermostat is calling for heat, NOTHING at all happens- no sounds of relays or pump running total silence- Does anybody any clues where to start looking for a fix please?
Many thanks

Gas engineer
 
1. Grateful for thoughts on the below:

2. Heating was not working as wanted. Not all radiators were getting hot. Six out of seven were getting hot. No air in system.

3. Persevered for a bit. Then the radiators started to only heat upstairs or down i.e. when all radiators were on only the upstairs would heat (four). Upstairs radiators off, downstairs would heat (three).

4. So we had our Grundfos Alpha2 pump replaced with a Grundfos UPS3 15-50/65 130. The Alpha2 had been in place for several years and used to display a 45 pressure reading when working normally. When the issues above started happening it could get no higher than 35.

5. As well as having the new pump fitted we went from an open vented system to a sealed pressurised system. Radiators were given TLC, re-balanced, chemically cleaned etc.

6. Success. Everything worked, so well. Our house had never been warmer. All radiators hot. Never experienced them that hot. This lasted for three weeks, then all of a sudden performance changes again. Back to picking either heating the downstairs or upstairs.

7. Bled the radiators. No air. The pressure reading in the sealed pressurised system was between 1-2. Kept monitoring for a week to see if there would be any changes in pressure to indicate an air lock. Nothing.

8. Decided to drain system and re-fill to see if that changed anything. Some success. Managed to get some heat (not the hottest they were during the 3 weeks immediately after the pump change and switch to pressurised system) into six of the seven radiators at the same time. Had to move between the various settings on the pump to eventually get six of the seven radiators hot. The only way to get the seventh radiator hot was to turn a couple of radiators off upstairs. Also, when the hot water came on via the ‘Timed’ setting the seventh radiator lost heat again.

9. It’s been suggested the Grundfos UPS3 15-50/65 130 pump might not be powerful enough and has overworked itself following the three weeks of initial ‘top’ performance.

10. The seventh radiator that is not heating, was the same radiator that had the problem originally before the pump change. In addition, the seventh radiator did not empty when the system was drained - appears to be set up in the system differently to the other six but does operate off of the Grundfos UPS3 15-50/65 130.

11. Also been suggested that maybe a power flush would be beneficial.

12. Boiler is located in the loft with the tank.

13. Anyone got any ideas on this one?
 
What speed is the pump on and no the pump is more than powerful enough can do 15 rads
 
Thanks for replying, Shaun.

So the old Alpha2 was always set to Constant III.

When the Grundfos UPS3 15-50/65 130 was fitted and the heating worked the best it has ever worked (for 3 weeks) that was also set to Constant III.

However, when the system was drained and re-filled in order to get heat flowing through the system again the pump was set to Proportional Pressure II (PPII) and Constant Pressure II (CPII). As when set to Constant III the pump was very noisy. Although being on CPII and PPII this got heat in the radiators were not hot, hot. Eventually went back to Constant III and the radiators got hotter and the pump was no longer noisy.
 
Further development - but mentioned above - heating not coming on at all if it overlaps with the hot water ‘Timed’ function. Will change them so they are on separately.
 
I have a weird intermittent problem where my oil boiler isn't firing. I have 3 x heating and one water zones on my time guard time clock. The zones seem to be powering correctly in that the zone thermostat lights up if the zone is on and the room temp is too low. When a zone is called I can see the two fuse spurs beside my boiler come on but the boiler doesn't fire. I think these are water pump and boiler spurs. I've had the boiler serviced and the boiler man says everything is good at the boiler, he thinks its and electrical fault.

I can get the boiler to fire by doing either of these:

1) Turning off the right hand fuse spur at boiler and then back on again.
2) Turning off all zones at the time clock and then turning them back on.

This is mainly a problem in the morning, when the boiler has fired it generally will fire throughout the day but this is intermittent as well.

To be honest I don't know if I need a plumber or a spark, any advice much appreciated.

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