Central Heating packed up over Xmas

[McFly]

Hi all first post in my search for help.
System has a Potterton profile 50e boiler. Mid position valve. Grundfos pump (fitted when shops reopened yesterday) Drayton RTS 1 roomstat (also changed)
New pump running and pipes to mid position valve and out from that are roasting.
Boiler fires up and heats ok but shuts off before downstairs rads get hot.
Any suggestions what to try next? Can force heat to downstairs by closing all lockshield valves on upstairs rads but still difficult to get all downstairs rads to heat.
Changed a Grunfos 15 50 for a 15 60 yesterday in desperation to try and increase flow also added a descaler to the expansion tank.

Does this sound like a boiler problem or is there anything else I can try?

Any thoughts will be much appreciated.

 

[ChrisR]

Sludge - suggest a search for background reading!

 

[bab]

u did put the diverter on the orrect way round? Did u drain a large rad b4 adding descaler as to drag it into system when u refilled it. Try htg only on clock then all upstairs rads off & only 1 downstairs on until hot . if very hot open up another downstairs & shut the hot one to confirm circulation. If u have a ballance valve from the flow 2 return near the pump & 3port valve close this first remembering how many turns to shut it so it can be reset when finshed,

 

[McFly]

I have not changed the diverter. And yes I beld off a few buckets full from the lowest point drain valve to hopefully pull the descaler into the system.

Current situation is. I think it is sludge causing the problem as black gunge from the drain valve.
Have turned off all lockshield valves upstairs and have got heat to the hall and 2 of the living room rads but nothing in the kitchen. Room stat in kitchen is set highest to call for heat and it clicks so assume power to it is ok. Why would boiler be switched off if temp not reached in kitchen?

Thanks for your time

 

[bab]

Ifu have flow from at least 1 rad then boiler will reach temp & switch off on its stat. turn off the rads that r working to try to increase flow pressure to non working rads, if there's a drain off on down stairs turn the boiler stat to off run the heating with the drain off open with a hose on it slowly not removing more water than what the ballvalve can keep up with, then open each downstairs rad in turn with all upstairs 1's off allow 10 mins on each rad & check colour of darin off for change in colour. if that don't work u may have to remove rads & flush them out outside, if u do have to remove them draw water through each valve until clean.

 

[kevplumb]

Why would boiler be switched off if temp not reached in kitchen?

because the water in the system is up to temp

 

[McFly]

Thanks for the reply. Not sure what the boiler stats is? Only thing I can see on the boiler is a switch that goes from 0 to max could that be it. If i turn this to 0 I assume that the boiler will not heat.
Tried draining some more from the drain valve downstairs and this is really black. Some heat did move to the kitchen rad But boiler now off again and kitchen rad cold.
How much should i drain off ? This will surely get rid of the descaler and protector which was added only yesterday. Is this what you mean?

Thanks again

 

[JohnD]

If you have used a chemical cleaner then (depending what sort) it will loosen the sludge and make the water look "dirtier."

Depending on the instructions you usually run the cleaning chemical for a few days before draining it all out and rinsing well, then add the anti-corrosion inhibitor.

It can be an advantage to drain and flush the system bedore adding the cleaning chemical, to wash out any loose stuff.

If the drain-off water looks really black that sounds good, because it is dislodging the sediment, which is what you want. But if it is really bad you may need to do it again. If you are badly sludged one of the best ways to wash it out is to take each radiator into the garden and blast it through with your hosepipe. This is of couse more work than just doing a chemical clean. You can also pay hundeds of pounds for a pro to do a "powerflush" with a big pump that squirts through your whole system without taking the rads off.

Easiest thing would probably be to buy another bottle of Chemical Cleaner in case you have such a lot of sediment that you need to do it twice. Sentinel and Fernox are good brands. Be sure to use Cleaner for this job, not Inhibitor, which is added only after cleaning and flushing are complete..

 

[McFly]

because the water in the system is up to temp

By the system up to temp are you saying that if 1 rad is up to temp the boiler will shut even though the stat room is not? From all your comments I am assuming that the boiler is working OK and heating up the small parts of the system it can reach the easiest. Sounds like a long and messy job to take off all the rads and wash them through but its probably the only way. Am confused as to why if I can get heat to a rad by closing off others there must be some route open even though it must be partially blocked. From that I would assume some heat to get through all the time but further away we go the inlet pipe is stone cold. Should the Grundfos 15 60 not have the power to push this round a small house only 4 rads upstairs and 4 downstairs?

thanks

 

[JohnD]

The pump should have enough power, but if you have a lot of sediment, it will obstruct the flow. If you are doing a chemical clean you can turn off all the rads except one at a time to force the circulation through that rad.

If you fancy doing a little light plumbing, you can buy and fit a Magnaclean which is a device for trapping sludge particles that are travelling round in the circulating water. It will cost you about £100.

 

[McFly]

Thanks for all your replies I am going out now to try and find a shop open that sell a really strong de scaler and will also try removing and blowing out the rads. Your advise has been much appreciated. Enjoy the rest of the holidays and have a great New Year.

ps really interesting site to browse through.

Will let you know how it goes

 

[McFly]

Sorry , back from non opened shops and at a loss now as have drained the chemicals
from yesterday

 

[JohnD]

The DIY sheds are probably open till 8.

If necessary you can run it on plain water overnight until you buy some more tomorrow. It will probably rinse out a bit more loose sludge.

Stir it up as much as you can with the pump before turning off the boiler and opening the drain.

 

[bab]

You need to be getting desludger rather than descaler. 2 different products. desludger will help 2 remove the iron oxide sludge by disolveing it into the water in the system as it pumps around. if u have parts of the system not circulating yet i recomend trying to get them all workin b4 adding the chemicals. forget whats already in keep it running with boiler thermastat on 0 while draining & filling to remove what u can first. 1 rad at a time try drawing water from both side's of rad if each rad has a drain off on it.

 

[McFly]

Hello all back again, no further forward. Don't know if anyone will pick up on this as its been a few days. Sorry but had to work.

Anyway. I have tried flushing out the system to reasonably clear water. Used Wickes rapid dose ch cleanser as it was the only thing I could get my hands on quickly. Sentinel and Fernox have been ordered on internet but not arrived yet. Also removed one downstairs rad and flushed through with a hose. As not an awful lot of sludge came out just black water I have decided due to the mess I created not to attempt the rest unless absolutely necessary. While system was drained down I took advantage and replaced the mid position valve which was playing up eg not always motoring when selected. Refilled system bled and turned on. Boiler fired up then tripped Air I am assuming due to lot of gurgling noises. Reset ok. Pump appears to be running full tilt. Boiler fires for about 5 /6 mins then stops. No hot water or heating though. Mid pos valve currently selected to both. Tried selecting either or but made no difference. First rad get hot. Hot water does not. Tried shutting down first rad to move heat but that seems worse than before. I am still thinking that the boiler is shutting down too early. Is that possible? Looks like after all the work and expense I will have to call someone out as the wife is getting well annoyed by now. Any further thoughts appreciated. PS Happy new year to all.