Power flushing 1 pipe system

[Christopher buzzard]

hey,

Set up - 3 storey house. Boiler in cellar, sealed system. Ground floor 2 pipe system, the rest of the house is 1 pipe. 2 radiators and 2 towel rails are no longer heating up. Approx 16 radiators in total.

So after fitting a new boiler, running system with cleaner in for a day. Hot flush. Cold flush. Left at night with all radiators heating. Got a call 2day to say 4 radiators aren't heating up. So balanced system on lock shields, still nothing. Even turning off all radiators, leaving the 4 on did nothing. It's just seems to be circulating on the 1 pipe system not entering the radiators back to the boiler. Pulled some water of the radiators, which after a time produced hot water. Both valves on the radiators are very old. But isolating the rad and opening both valves produced water. All be it very black. So the valves are allowing water to flow. I've decided to go back on Monday to powerflush the system. So my question is how can I do this. Powerflushed 2 pipe systems many times but not 1 pipe. How do I stop it circulating around the pipework and into the radiators.

Thanks for your time.

 

[ShaunCorbs]

did it work before you installed the new boiler?

 

[Harvest Fields]

I was told that you cannot powerflush a one pipe. It will not clean it properly?? But I have been wrong before?

 

[ShaunCorbs]

I was told that you cannot powerflush a one pipe. It will not clean it properly?? But I have been wrong before?

Not very good anway you really can only do the main run and not to the rads

 

[Christopher buzzard]

I was thinking that. Yes they all worked so the owner said. Although I never checked them before because I had no reason to. The boilers flue had rotted away and no spares so had to replace boiler. But think maybe it's the 1st time it's been drained down in like 10 years. No fernox/filter ect. So proberly powerflushing will be wasting my time? Any other ideas? I've changed the pump with one I had on the van to see if it makes any difference over the weekend. Here's hoping!

 

[ShaunCorbs]

Have you tried turning all the other rads off eg the two pipe circuits

 

[the_d_o_t]

Yer one pipe system it will just whizz round the pipe without entering the rad.

Unless you install a gate valve in between the two tees of the rad for each rad 😵 ha
But that’s just madness haha

 

[the_d_o_t]

Was the system a sealed system before you installed the new boiler?

 

[Christopher buzzard]

Yeah sealed for 10+ years. The water from the initial drain down seemed pretty clear. Yes had all the rads turned off apart from the 4. It was returning back to the boiler fine. Just not through the radiators. Tiled floors in the rooms where the radiators aren't heating up. Nightmare!

 

[Last Plumber]

Yeah sealed for 10+ years. The water from the initial drain down seemed pretty clear. Yes had all the rads turned off apart from the 4. It was returning back to the boiler fine. Just not through the radiators. Tiled floors in the rooms where the radiators aren't heating up. Nightmare!

The rads on a one pipe work by gravity so no, you can't powerflush them. You will need to take them outside and hose them out.

 

[Last Plumber]

Are the valves getting warm?
If they are it will be some sort of restriction on the branches or in the rads.
Are the rad valves the correct type?
If you have normal rad valves designed for a two pipe system installed on the one pipe system, they may not allow enough of a gravity flow out of the rad.

 

[Gasmk1]

age old worked fine before you came, 10-1 they didnt work fine but you are stymied i would go down the routs of cleaning th e4 out individually and also running through the valves if one pipe they nee to be full bore so if trv's they may be the wrong ones.

 

[Deleted member 44451]

hey,

Set up - 3 storey house. Boiler in cellar, sealed system. Ground floor 2 pipe system, the rest of the house is 1 pipe. 2 radiators and 2 towel rails are no longer heating up. Approx 16 radiators in total.

So after fitting a new boiler, running system with cleaner in for a day. Hot flush. Cold flush. Left at night with all radiators heating. Got a call 2day to say 4 radiators aren't heating up. So balanced system on lock shields, still nothing. Even turning off all radiators, leaving the 4 on did nothing. It's just seems to be circulating on the 1 pipe system not entering the radiators back to the boiler. Pulled some water of the radiators, which after a time produced hot water. Both valves on the radiators are very old. But isolating the rad and opening both valves produced water. All be it very black. So the valves are allowing water to flow. I've decided to go back on Monday to powerflush the system. So my question is how can I do this. Powerflushed 2 pipe systems many times but not 1 pipe. How do I stop it circulating around the pipework and into the radiators.

Thanks for your time.

 

[Deleted member 44451]

i have had this many times and come to the conclusion its a waste of time the only way to clean rads on a one pipe is to take them off and flush them individually

 

[the_d_o_t]

One pipe systems work best with swept tees and trv in Let at the top of rad and locks bottom of rad.
But as much as you want to say “well yer it worked before so it has to work again now” it’s a old system that is not to manufacture instructions. You won’t find in the MI a onepipe system.
Get it upgraded

 

[Harvest Fields]

Had to upgrade lots to two pipe. Did you know it was a one pipe before fitting the new boiler? Sorry if you have answered this already. Not read back through all posts.

 

[Christopher buzzard]

@Harvest Fields no I didn't. Down it the cellar it's a S plan and I can see where they have taken off for each rad on a 2 pipe system. But up stairs pipework is under the floor and pop up with trv and lock shield for each rad. It was until these 4 didn't work with all other rads switched off that I realised its was 1 pipe system. @supaplum @Gasmk1 pthanks for the tip. I will take the radiators off on Monday to flush out separately. Do you suggest that with each rad off, I should run some water through each valve to clear any muck? It's hard to say if swept tees were used as pipework is under tiled floors on the 4 that aren't working. @Last Plumber it gets a little warm up to the valve trv but nothing else. I will get a picture of the trv's used. They are an old bulky valve, none I've seen before (18 years plumbing) with a fairly new Honeywell thermostatic head screwed on.
Thanks for all your help and time. It's really appreciated. I'm the only plumber left on my firm with no1 left to ask these questions. All retired.

 

[Last Plumber]

@Last Plumber it gets a little warm up to the valve trv but nothing else. I will get a picture of the trv's used.

Ok.

 

[Christopher buzzard]

Theses Are the valves on radiators. Any1 seen the trv before? I took the 4 rads off today. Flushed them. So much sludge inside them, put them back on and now working fine. Trouble is their hotter then the rest of the rads now. So gotta go back in the new year to take off and flush all rads.

 

[Jim Goodenough]

All v interesting for me 🙂

 

[thereisawizza]

Hate to play Devil's Advocate here but prior to fitting the boiler did you feel you had could have sucessfully cleaned the system to BS7593? Maybe it's just me but if I can't do a proper powerflush, it's a new system or let someone else have the job