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Discuss Single pipe system blocked ? in the Central Heating Forum area at PlumbersForums.net

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12
single pipe system pipework blocked ? System is 7 rad single pipe in a bungalow fed by Worcester combi boiler. After many years of being hottest house on earth rads are struggling. Service engs [ same ones for many years] have changed pump , cleaned with sentinel 800 [ though i don't believe it was carried out correctly with regard to correct flushing / draining ] They believe the pipework is fouled and have recommended a full system pwk change to a 2 pipe system , obviously at considerable cost. The system is in my mother's house but I've spent some time there and carried out following trials.******..Left system running with a single rad on line for 30 mins , repeated for each rad in the house. Every rad heated up fully. To me this means there is some sort of route thru all the system pipework. The engineers have agreed to carry out a further wash at reduced cost but following job method that I have supplied them from both Sentinel and Fernox , may use a fernox product this time.*********...Any thoughts ?
 

cjg

Plumber
Messages
380
if you have altered the lock shields then you have to re balance the whole system,
water goes the fastest way it can, so it will pass the rads return to the boiler, then your rads don t get hot,
you need some one who knows the job.
 

Last Plumber

Esteemed
Plumber
Gas Engineer
Messages
4,220
To flush that they would need to take the rads out one at a time and clean them outside with a hose or similar method in my opinion.
I obviously cannot say for certain as I haven't seen the job but an engineer on site should be able to tell if the pipework is blocked without guessing.
 
Messages
12
if you have altered the lock shields then you have to re balance the whole system,
water goes the fastest way it can, so it will pass the rads return to the boiler, then your rads don t get hot,
you need some one who knows the job.
I've looked into balancing issues and initially ruled it out as no individual rad is getting excessively hot , 6/7 rads have TRV'S fitted and 3 rads are turned fully off all the time so even though I'm not sure of order of flow I would be surprised if this was the issue.
 
Messages
12
To flush that they would need to take the rads out one at a time and clean them outside with a hose or similar method in my opinion.
I obviously cannot say for certain as I haven't seen the job but an engineer on site should be able to tell if the pipework is blocked without guessing.
rads don't seem an issue as fully heating up when lined up individually.
 

Gasmk1

Gas Engineer
Messages
1,817
Look up one pipe systems the normal pipe up is top bottom and trv’s should Be full flow
 
Messages
12
Look up one pipe systems the normal pipe up is top bottom and trv’s should Be full flow
thanks for your help , will have a chat with engineer when he comes but i'm unaware of any changes made since system was working perfectly so can only assume design and hardware are not an issue.
 
Messages
12
If all was working well once, it is now almost certainly a balancing issue.
As I understand it a balancing issue is where individual rads take lions share of hotter feed , normally at the start of the loop , leaving other rads further downstream to be fed with cooler water. Surely if this was the issue at least 1 rad would be excessively hot and this is not the case.
 

Ben-gee

Esteemed
Plumber
Messages
1,892
Or on a one pipe too much heat goes straight back to boiler - think of the boiler as being your ‘one excessively hot radiator’.
 

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