Downstairs radiators red hot, upstairs just warm and spur radiators stone cold??

[ttyrie]

I have had a problem with my domestic central heating system for the last 4 years but have not been sucessful in sorting it out.

Basically the downstairs radiators are always red hot and the upstairs radiators are mostly cold with an exception to the bathroom which is hot and bedroom one which is OK but not great.

I also have 2 spur radiators that go from the upstairs pipework straight through the wall into the roof space of the single story kitchen extension with a 19 foot lenght and down the 8ft stud wall teed off and shared between 2 radiators (one in the cloakroom and one in the WC (both of these radiators are always stone cold with no heat whatsoever apart from when the upstairs radiators get full of air.

I have a main radiator in the kitchen which is the first radiator in the downstairs sequence and this is always very hot along with the rest of the downstairs ones.

I have tried bleeding the radiators out, force pumping the spur radiators (which does make them get very hot) I have configured the downstairs radiators so the main valve just lets a trickle of water in and so that the downstairs get very hot but this still doesnt seem to have enough pressure for water to go upstairs. The pump is also on the highest setting possible.

I can confirm that I did drain down the whole system about 2 years ago and added Sentinel sludge remover and ran the system on hot for about 1 hour and drained the system out and refilled and added Sentinel inhibitor and the system was working a little bit better but now it is worse than ever (especially now it is so cold in the cloakroom & WC)

I also notice that the boiler does make some knocking and bubbling noises when it is running (could this be limescale? air bubbles?

If I could have a some help with this then that would be great. Would my system need a proper clean by removing all the radiators and flushing out with a hosepipe and leaving the cleaning solution in for a numbers of days?

My boiler is:- Potterton Kingfisher MF RS RS70 Floor Standing Gas Boiler (BoilerShop Potterton Kingfisher MF RS RS70)

And the whole system was installed in 2000 by the previous owners of the house (I have been here for 4 years)


Thanks there

 

[GrahamM]

On your initial description sounds like the system is too big for the pump or pump on way out or both. What size pipework is run to radiators and how many radiators do you have.

 

[ttyrie]

I have 15mm pipework, and 11 radiators (4 upstairs and 7 downstairs)...

 

[dontknowitall]

As GrahamM was suggesting perhaps the upstairs circuit should be 22mm with 15mm tails to/from each radiator instead of 15mm all the way through.

Another possibility is the system is poorly balanced. You could look up balancing radiators and on some of the threads there are links for helpful instructions on how to do this.

 

[ttyrie]

Looks like a plumber will be needed to have a look at it.....

 

[ttyrie]

I have just ripped up the floorboards upsatairs and looked at the size of the pipes- it is 22mm with 15mm tails to each and every radiator.

My pipework to the spur radiators may need altering? if so could i have some advice as where they would best be added to? Do you have a pump you would reccomend as the pump is very small and is probably on its way out...

 

[dontknowitall]

Pipework sounds fine - I'd now suspect the pump. Grundfos ones (market leader) are around £75 and take about an hour to fit, assuming no problems.

 

[Billy Bob Bob]

you need to get someone in it could be the pump or something more fundamental like boiler gas pressures under set

 

[ttyrie]

Would gas pressure affect the boiler controls?

I also forgot to mention I have a problem with the boiler control panel and have to complete the following steps each morning I switch the central heating on.

1. Switch the water off at the control panel.
2. Turn the central heating on at the control panel.
3. Turn the water on at the control panel.
4. Switch the boiler off at the switch for a few seconds.
5. Switch the boiler back on at the switch and the central heating will then start up.

If you dont do these steps and switch the CH on as normal then it will just pump the the cold water around the radiators but it will still heat the water in the cylinder.

It started doing this last christmas and it does get pretty annoying becuase I cant have the timer on becuase it will not start.

Do any of you people have any idea what may be causing this? Could it be the gas pressure?

Turning the heating on and off normaly would be a start before I start giving the system a good clean.

I was planning to remove all of the radiators and flushing the sludge out of them with a hosepipe, clean and replace the bits in header tank, adding cleaning fluids to the system for a few weeks, descale the boiler, drain the system out a few times then refill and add inhibitor etc....


Any advice again will be much appreciated.....


Thanks

 

[Billy Bob Bob]

LOW OR OUT OF SPEC GAS PRESSURES WILL GIVE POOR TEMPERATURES TO THE RADIATORS,in regards to your other fault that sounds like something else if it was a pump causing this i would expect upstairs rads to get hot not downstairs

 

[ttyrie]

Does anyone have any ideas about the boiler not switching on properly???

 

[PlumbBobBob]

could be sludge as you say you only left cleaner in for an hour before flushing out and refilling. should have been left in for a couple of days at least. imho

 

[ttyrie]

I will do as I posted before and give the system a thorough cleaning and alter the pipework to the spur radiators so that they are fed directly from the kitchen radiator instead of upstairs where gravity might stop the water being pumped back up an 8ft wall and along an 19 ft run..

I will post back here when I have cleaned the system out properly and altered the pipework and let you know the results.

Out of curiosity how much on average would a boiler service cost as I dont think it has ever been serviced since the system was installed in 2000... I am located in Bedford.


Thanks

 

[ttyrie]

I have had a look at the Central Heating header tank and it is full of black/ brown water with sludge in the bottom.

I will be spending a day at the weekend removing all the radiators and flushing them out with a hosepipe, run some water into a bucket from each radiator valve to remove any loose sludge, completely dismantling the header tank and give it a thorough clean and replace the ball valve if necessary.

Also is it possible to remove the Central Heating pump and clean the inside of it out? It looks exactly the same as:- Grundfos 15-60 Domestic Circulating Pump - NoLinkingToThis, Where the Trade Buys


Once I have rebuilt all of the system I will be adding a chemical cleaner but would like some reccomendations of which cleaner to add to my system and how long to leave it for.

Also will the chemical cleaner be able to clean the heat exchanger and stop the kettling/ banging noises?

Final 2 things- Is there anything I can add to the system to automatically remove the air from the system? Is there any way to stop the sludge building up again?


Thanks

 

[ttyrie]

I have had a look at the Central Heating header tank and it is full of black/ brown water with sludge in the bottom.

I will be spending a day at the weekend removing all the radiators and flushing them out with a hosepipe, run some water into a bucket from each radiator valve to remove any loose sludge, completely dismantling the header tank and give it a thorough clean and replace the ball valve if necessary.

Also is it possible to remove the Central Heating pump and clean the inside of it out? It looks exactly the same as:- Grundfos 15-60 Domestic Circulating Pump - NoLinkingToThis, Where the Trade Buys


Once I have rebuilt all of the system I will be adding a chemical cleaner but would like some reccomendations of which cleaner to add to my system and how long to leave it for.

Also will the chemical cleaner be able to clean the heat exchanger and stop the kettling/ banging noises?

Final 2 things- Is there anything I can add to the system to automatically remove the air from the system? Is there any way to stop the sludge building up again?


Thanks

Forgot to mention- how much does a boiler service cost on average?