I have a Potterton Suprima 70. The boiler comes on and heats water/rads up as normal. In this weather I generally knock both onto constant. What happens then is the boiler will get upto a certain temp and then cuts on and off. It will run for circa 20 seconds then cut out for about an minute. it will then keep repeating this. The pump keeps running and the rads get cool/DHW will not re-heat. I changed the OH stat in the boiler last year when this problem occured. Someone suggested I may have a bit of sludge in the boiler pipes and this is the cause. Anyone any ideas??
Potterton Suprima 70 Intermittant Fault
- Thread starter Marky
- Start date
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Thinking of getting new pump (Grundfoss 1550 at present) as is noisy. Boiler is in loft and I think pump struggles to pump over 3 stories. It is on max. Also as boiler is in loft - header tank for CH is circa 2 feet above boiler so would this cause air ingress? System is also noisey. What would bleeding to HW do?
Last thing first - air can cause lack of circulation, and noise, and a common place for it to accumulate, and matter, and not get noticed, is in the primary pipes to the hw cylinder. Usually there's a stub of pipe with a bleed point on the top.
You have to be careful with the pipe layout when the boiler is so near the f/e tank vertically - see the boiler instructions (downloadable). This is likely to be the problem if the noise is caused by air in the pipes - which sounds like gravel slushing about
Knackered pumps make a droning noise - try a stick between the pump and your ear to listen for it. If in doubt I would change the pump for a 15-60.
Sludge is a likely culprit. Do you have to bleed rads frequently, and do you get black/red water?
You have to be careful with the pipe layout when the boiler is so near the f/e tank vertically - see the boiler instructions (downloadable). This is likely to be the problem if the noise is caused by air in the pipes - which sounds like gravel slushing about
Knackered pumps make a droning noise - try a stick between the pump and your ear to listen for it. If in doubt I would change the pump for a 15-60.
Sludge is a likely culprit. Do you have to bleed rads frequently, and do you get black/red water?
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ChrisR said:
can you also not use a long / large screwdriver as mechanics do?
Cheers for the advice - feel I am slowly getting there.
There is a bleed valve on the flow to the HW cylinder. Every time I check this water comes out.
It does sounds like gravel slushing about when running, I have auto bleed valves on the flow and return on the top of my boiler to try and minimise the air in the system. The vent & feed and header tank are 15 feet from the boiler, but only 2 feet higher.
Is there anything else I can do to try and minimise this problem - or should I just take a look at the boiler manufacturers instructions?
I do not have to bleed the rads frequently.
I emptied the system a few weeks ago and flushed it through with clean water and the water did not seem too bad - light brown. When I take off the rads to decorate sometimes there is a little sludge in the bottom of the rads which I will wash through, so I try and maintain the system ongoing. Is there anything I can do to get rid of sludge?
I am also going to change the pump anyway as I don't think it is powerful enough.
There is a bleed valve on the flow to the HW cylinder. Every time I check this water comes out.
It does sounds like gravel slushing about when running, I have auto bleed valves on the flow and return on the top of my boiler to try and minimise the air in the system. The vent & feed and header tank are 15 feet from the boiler, but only 2 feet higher.
Is there anything else I can do to try and minimise this problem - or should I just take a look at the boiler manufacturers instructions?
I do not have to bleed the rads frequently.
I emptied the system a few weeks ago and flushed it through with clean water and the water did not seem too bad - light brown. When I take off the rads to decorate sometimes there is a little sludge in the bottom of the rads which I will wash through, so I try and maintain the system ongoing. Is there anything I can do to get rid of sludge?
I am also going to change the pump anyway as I don't think it is powerful enough.
The temp sensor could be faulty so the boiler turns off too quickly - does its flow pipe get scorchio (82ºC is hot!)?
You can get a hard sludge build up around where the feed pipe joins the circuit, which stops circulation - see where the heat goes. Heating the pipe locally with a torch shows it up - the hot bit doesn't spread as well as in a clean pipe.
Sounds like you could be sucking air down the vent, try holding a glass of water up under it. Blockages elsewhere can make that happen. Also look at the instructions! (pdf download on either Potterton or Baxi site).
You can get a hard sludge build up around where the feed pipe joins the circuit, which stops circulation - see where the heat goes. Heating the pipe locally with a torch shows it up - the hot bit doesn't spread as well as in a clean pipe.
Sounds like you could be sucking air down the vent, try holding a glass of water up under it. Blockages elsewhere can make that happen. Also look at the instructions! (pdf download on either Potterton or Baxi site).
Yes flow does get hot. Changed temp stat in boiler - someone old me I do not need to put conducting paste in when changing it so I did not. Would this have an effect?
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