Newbee. CH Rad/Pipework heat problem.

[Philbee]

Hi chaps
I have a problem, hoping for some additional advice.

Open vented CH system, Baxi Bermuda back boiler to 8mm microbore, solid ground floor.

Hall rad downstairs and two rads upstairs now won't get hot or the pipework (all front of the house).
Hall downstairs dropped leg started off cold both sides. Removed Rad flushed, bucket tested valves all ok reinstated and bled system. Two front beds started off being warm up top cooler bottoms.(also thought sludge so removed and flushed). Bucket tested all the valves and found to be ok. Shut all hot Rads down hoping to feed cold Rads. No joy ( thought Pump due to age) New Grundfos UPS2 15-60 fitted with new pump isolators. Flushed whole system and now have Sentinel X400 in system 24/7 normal temp now 2 days in. System bled two days in a row cold, also pump just to make sure it wasn't air.
G/F airing cupboard in kitchen with boiler , kitchen Rad is a bypass(hot) G/F Back of lounge dropped leg( hot). Upstairs bathroom Rad (hot). Upstairs back bedroom(hot). Everything to the front of the house is cold Rads, and pipework.

Any ideas where I go from here?

Assume upstairs is a two pipe system, don't know if fitted with manifolds or just 8mm take offs.
There is a dead dropped leg where I removed a rad in the front of the lounge removed rad and capped pipes off separately sometime ago, but the heating has been ok since that was done.
Is there anything else I can try before opening floor up to identify pipe runs etc. It has been working fine for years until now, but does suggest maybe a blockage somewhere, or could it be air trapped in the front end of the house section somehow?
Hoping for suggestion of something else I can do without the hassle of opening up floors .

Sorry for the long 1st thread, but thanks for any feedback received.

 

[Chuck]

Open vented CH system, Baxi Bermuda back boiler to 8mm microbore, solid ground floor.

Microbore systems are very susceptible to blocking with sludge. An open vented system will generate a lot of sludge. When the inevitable happens attempts to clear blockages by flushing are rarely susceptible in my experience.

If you are lucky, you may be able to locate the blockage with a strong magnet but I think you are going to have to resign yourself to spending a significant amount of time tracing pipework and testing it section by section.

Even if you get it working, it's still going to be an open-vented microbore system, which is not something I'd want in my house. I think you should consider re-piping and converting to an unvented scheme.

 

[Philbee]

Hi chuck

Thanks for the reply. In 25 years with this microbore and no probs I can hardly say it's been problematic. We live in a soft water area so maybe that's why.
I suppose this current problem is down to my past years of lack of maintenance . If I can sort this out short term, I doubt I will need to do it again, just take better care of it.

So do you think it's floor up time? No more suggestions.

 

[Riley]

I think your lack of problems has been more to luck than anything. Microbore is horrible stuff and blocks in a flash. I’d be more tempted to sort it properly and upsize pipework and change to a sealed system if it’s feasible

 

[Clint B]

you could always try a thermal imaging camera before digging up the floor, may identify where the heat is actually getting to and therefore possible problem area.

 

[Rob Foster]

try flushing it with mains pressure and do it aggressively ie. turn all rads off bar one and direct the mains pressure round each mini circuit . if you dont know what I mean ask more. you will need outside tap to a drain off for incoming, and a remote drain off to direct the outgoing into a big bucket or preferebky onto some concrete outside to see if the ferric sludge is coming out, go round rads and exposed pipes with a rubber mallet bang gently and also strong magnet , if there are already chemicals in the water usually it brings wriggly worms out of the nearby soil until they expire . this might should take all sunday but could save you a fortune....Rob Foster aka centralheatking

 

[Philbee]

try flushing it with mains pressure and do it aggressively ie. turn all rads off bar one and direct the mains pressure round each mini circuit . if you dont know what I mean ask more. you will need outside tap to a drain off for incoming, and a remote drain off to direct the outgoing into a big bucket or preferebky onto some concrete outside to see if the ferric sludge is coming out, go round rads and exposed pipes with a rubber mallet bang gently and also strong magnet , if there are already chemicals in the water usually it brings wriggly worms out of the nearby soil until they expire . this might should take all sunday but could save you a fortune....Rob Foster aka centralheatking

Hi Rob
Thanks very much for giving such a detailed description of work, will give it a try tomorrow.

 

[Philbee]

Hi Rob
Thanks very much for giving such a detailed description of work, will give it a try tomorrow.

 

[Rob Foster]

go for it and report back please
usual rules apply,here....do job
it will be a winner..reward yourself after 4x cans
if you get hooked up I am about
tomorrow as are my friends
Rob Foster ...aka centralheatking

 

[Philbee]

Hi Rob

After trying your suggestions and not getting any better results I decided the only way was to open the floor up.
I found that the previous installer had put two drop bypass sections into the 15mm flow and returns to bypass 4 22mm supply pipes. I thought that over a period of time due to the bent radiuses and depth of deflection this could actually be where the blockage could be.
I cut the two sections out to find that the return pipe was indeed blocked. This was also impacted by the fact that that FE tank which had a 4 Mtr head feed was teed into the return before the bypass drop sections. It would appear that the FE tank feed restricted the flow of the return causing a build up up sludge.
I repiped the FE tank feed into part of the 22 mm return to the boiler which it should have been done before, and replaced the drop bypass using 45degree offset endfeed copper fittings.
I also repiped the Hall rad in 15mm and increased the 15mm feeds just leaving approx 300mm feeds to rads in 8mm to reduce the added expense of changing all the valves etc.
The dead leg to the redundant lounge rad was isolated and made the upstairs bed room rad the last in line.
The result is a more efficient system heating up to full potential in only 10 mins.

Result.

Thanks to everybody that gave advice.
Cheers
Philip

 

[Rob Foster]

Hi Rob

After trying your suggestions and not getting any better results I decided the only way was to open the floor up.
I found that the previous installer had put two drop bypass sections into the 15mm flow and returns to bypass 4 22mm supply pipes. I thought that over a period of time due to the bent radiuses and depth of deflection this could actually be where the blockage could be.
I cut the two sections out to find that the return pipe was indeed blocked. This was also impacted by the fact that that FE tank which had a 4 Mtr head feed was teed into the return before the bypass drop sections. It would appear that the FE tank feed restricted the flow of the return causing a build up up sludge.
I repiped the FE tank feed into part of the 22 mm return to the boiler which it should have been done before, and replaced the drop bypass using 45degree offset endfeed copper fittings.
I also repiped the Hall rad in 15mm and increased the 15mm feeds just leaving approx 300mm feeds to rads in 8mm to reduce the added expense of changing all the valves etc.
The dead leg to the redundant lounge rad was isolated and made the upstairs bed room rad the last in line.
The result is a more efficient system heating up to full potential in only 10 mins.

Result.

Thanks to everybody that gave advice.
Cheers
Philip

well done you a tricky job well
executed and thank you for reporting back ...it means a lot to us at UKPF ...Rob Foster
aka centralheatking