Certain radiators on same loop not heating up - tried balancing, draining, flushing..

[Mtbamplumb]

Hi all,

Have a problem with several of my radiators that had been plagueing me for the past couple of months.
Summary:

• 4 radiators on same loop fed from 1st floor
• 2 on first floor (landing & Livingroom)
• 2 drop down to ground floor(entrance hall & Kitchen)
• 3 intermittent (entrance hall, landing, living room- worst of 3)
• 1 very very intermittent, only work for a couple days then stop (drop down to kitchen)
• all other rads get piping hot, and when check valve opened only a little get hot and maintain temperature
• 3 story house
• grundfos UPS 25-55/ 180 pump

Actions already taken:

• tried balancing the system, 3 of 4 started to get warm, 1(drop down to kitchen) will not warm up
• Bled all rads numerous times
• fully drained and refilled system, re balanced
• drained biggest problem on , Kitchen rad which has drain and topped up system to see if air lock, got warm but didn't stay warm
• Replaced thermostat valve on kitchen rad.
• flushed system with hosepipe, and tried also flushing each rad in turn by closing all and having 1 open at a time.
• removed 2 problem radiators and jet washer flushed to remove sludge
• took pump off and checked impellers
• Pushed up pressure to 2 BAR to no avail
• pump set on maximum speed setting

Main problem radiator(kitchen) only seemed to get to work for couple days by turning all other rads off, draining water from drain valve, leaving thermostat valve closed and check valve open, bled radiator until was full of hot water.

ANY SUGGESTIONS ARE GREATLY APPRECIATED.

regards

Mtbamplumb

 

[doitmyself]

Re: Certain radiators on same loop not heating up - tried balancing, draining, flushi

How far open on the lockshield valves?

What was the water temperature when you balanced?

Did you remove the TRV heads when you balanced?

 

[lame plumber]

Re: Certain radiators on same loop not heating up - tried balancing, draining, flushi

need to check if pipe sizing on circuits is big enough to come with number of rads using each circuit, ie 4 rads on 15mm loop is normally too many or if micro bore, have addl rads been added to a micro bore loop?.

 

[Mtbamplumb]

Re: Certain radiators on same loop not heating up - tried balancing, draining, flushi

Hey guys thanks inks for your replies,

doitmyself: lock shields fully opened on problem rads.
not measure exact temp when balanced but boiler registering around 67degrees. Rads hot to touch
TRV's on problem rads taken off to see if problem lies with them but no change.

lame plumber: listen floor boards, not sure of exact sizing but main pipe leading from manifold on problem loop is definitely minimum 15mm pvc if not bigger, pipes then leading off this loop to rads is 10mm copper piping.
house has not had additional rads added.

thanks again for your help guys, anything else please let me know.
cheers

 

[PhoenixServices]

Re: Certain radiators on same loop not heating up - tried balancing, draining, flushi

When you say it is a manifold feeding the rads, is that a manifold that all of the problem rads go off from? or are all the problem rads off one flow and return from the manifold?

 

[Mtbamplumb]

Re: Certain radiators on same loop not heating up - tried balancing, draining, flushi

Hi Pheonixservices,

have not seen the manifold but all the problem rads lead from the same pipe which leads to what I believe is the manifold.

 

[jtsplumbing]

Re: Certain radiators on same loop not heating up - tried balancing, draining, flushi

If you have a manifold system you should have 2 of them, one for flow one for return, 22mm into manifold 10mm out to each radiator, need to locate manifolds & see if that is where they are blocked

 

[Millsy 82]

Re: Certain radiators on same loop not heating up - tried balancing, draining, flushi

Have you removed the radiators and connected a hose pipe to the valves and pull water through each valve? Sometimes this will shift a partial blockage if it doesn't you may find that it will show you where the problem is. I have in the past connected a compressor up onto a pipe but I wouldn't recommend that it was very squeaky bum time but my boss told me I had to do it so it was up to him.

 

[Mtbamplumb]

Re: Certain radiators on same loop not heating up - tried balancing, draining, flushi

Jtsplumbing: there are two seperate pipes, 1 flow and 1 return and they look to be about 22mm and then the feed off the flow and back to the return on at least 1 rad looks to be about 10mm. Problem is some of the rads on this loop have been working. So not sure why 1 is intermittent and 1 is a persistent problem.

Millsy82: I have connect a hosepipe and tried flushing the system, but not from each rad. One thing to note is that I have tried draining the main problem rad by firstly closing the check(flow side) and leaving the try fully open, and then again in reverse. Both times good pressure came out and pressure dropped on system rapidly.


seem to be running out of ideas, so appreciate your help all.

 

[jtsplumbing]

Re: Certain radiators on same loop not heating up - tried balancing, draining, flushi

So did you find a manifold ? or is each feed to each radiator just Teed off the 22mm pipe ? is 10mm pipe copper or plastic ? could be blockage where pipe is reduced or even a kink in 10mm,

 

[DrainMedic]

Re: Certain radiators on same loop not heating up - tried balancing, draining, flushi

Has the system ever worked correctly? If it has, then pipe sizing etc is ruled out initially.

If you turn all the rads off completely, leaving just one of the problem rads open, then this will rule out blockages in the pipework if that rad gets hot. Then try turning a second rad on, and the first rad off, each rad that gets hot in this way will be ruled out from having blocked pipework.

Have you checked that all the TRVs are operating and not stuck shut? It's always worth leaving the heads off the TRVs while you're fault finding.

It's definitely worth shutting the top floor rads down as far as possible so they're just cracked open.

Is The pump pumping with the natural flow of the system? It might sound daft, but if the pump is on the flow side pumping down, then it's going to fighting the natural flow of the water, with the hot water wanting to rise. I've seen dozens of pumps over the years mounted in reverse that cause no end of problems!

 

[Mtbamplumb]

Re: Certain radiators on same loop not heating up - tried balancing, draining, flushi

Jtsplumbing: each rad tees off the 22mm plastic pipe. The 10mm is copper pipe. I will try see if I can find any kinks but most of the 10mm goes into the walls or drops drop from the first floor into the walls.

Drainmedic: thanks for your replies. Have tried shutting all but one off and got hot water into it after loads of draining and bleeding. It worked for a couple days then stopped. I have done this a couple times. Also balanced top floor so that the valves are just cracked open but didn't seem to help.
vhecked the pump direction as you indicated and pumping with the flow from what I can see.

thamks again for your replies guys . All the tips are good to know and double check.

 

[DrainMedic]

Re: Certain radiators on same loop not heating up - tried balancing, draining, flushi

I really hate to say it, but you seem to have ruled out everything but the 'P' word! Has it been powerflushed? Or is there any hint of sludge or crud in the system?
I went to one about 3 weeks ago that someone else had 'Powerflushed' and eventually found a pipe in a void under the floor had become literally completely blocked, I couldn't shift it so just replaced the pipe, but the symptoms were identical to yours and no less than 5 other plumbers had been out to it, including the specialist 'Powerflusher'.

 

[jtsplumbing]

Re: Certain radiators on same loop not heating up - tried balancing, draining, flushi

A long shot ! I know you have removed pump , but how old is it ? just because impeller is going round doesn't mean its working correctly try a new pump

 

[Mtbamplumb]

Re: Certain radiators on same loop not heating up - tried balancing, draining, flushi

Hi guys!

thanks for your replies.
Night before last I drained about 4 buckets loads of water from the main problem radiator whilst topping up the system. The other 3 on the loop that were not working properly then started working. Ran it over night and all but the key one was working. Then turned it back onto timed and when came home last night all looked good except the key problem rad. Then tonight come home and the 3 intermittent rads not working. Pain in the neck.

drain medic: not power flushed but might try that, Havel tried draining from each side of each rad, flow and return and they all flow with good pressure and very little sign of sludge.

jtsplumbing: replacing pump is one of my options I will certainly keep in mind, but does not explain why all other rads are piping hot so that why reluctant to shell out £300 quite yet on a new pump.

looks like need to get a circular saw to pull up a few more floorboards to check the rest of the pipework.

keep suggestions coming guys, greatly appreciated. Thanks,

 

[jtsplumbing]

Re: Certain radiators on same loop not heating up - tried balancing, draining, flushi

Don't know where you intend buying a pump, but you need to check on price £300 ! are you having a laugh,?

 

[doitmyself]

Re: Certain radiators on same loop not heating up - tried balancing, draining, flushi

I assume the pump is on the middle floor.

How are the other floors fed? One feed to each floor and rads teed of that, or individual feeds to each rad?

Make and model of boiler?

How are you balancing the system?

 

[Mtbamplumb]

Re: Certain radiators on same loop not heating up - tried balancing, draining, flushi

Hi doitmyself,
pump is on the ground floor, feeds then up to first floor and then up to second floor.
i believe that then the is a manifold which has 2 branches leading too the first floor. 1 being the problem loop, the other leads to 2 bedrooms and an ensuite. Then off this same loop there is a drop down to the study and guest toilet on the ground floor.

The main feed continues up to the second floor and feeds 4 rads on the second floor which all get nice and hot.
I have now just fitted automatic vent valves to the problem rads so going to see if that helps.

anymore tips greatly appreciated, cheers for all your help.