Return from rad not warming up.

[Beanz08]

In the past i've had sludge type problems with my CH and have tried sentinal products to rectify it which to a degree worked but not 100% which i think is down to the microbore piping. Also in 2005 i had a new boiler and asked to have the system powerflushed which they did and at the time i thought it was done correctly, but since have realised that the 50 or so minutes they connected it up for was nowhere near as long as it should be on for !

Anyway to my problem.
One of the rads is in a sort of C shaped room and still never heats up at the bottom so after trying to flush with a hose - not enough pressure tho - i decided as all my rads are single panel i might as well bite the bullet and try fitting a double panel in its place hoping the extra BTU would be more than sufficient to heat the whole room.
I hung the rad nicely and connected up the piping no problem filling the rad and bleeding all air til water ran through.
Then when i turned on the CH the TRV pipe heated up pretty quick but the rad didn't, after about 20 minutes the top of the rad was warm at best and that was about it. I noticed that the lockshield end was as cold as it had been before.

What are my likely solutions ? I'm guessing i have a blockage in the return pipe so when i have time i planned to get the room half empty to get up the carpet and bit of floorboard to see how much piping there is to where it meets the main return pipe as i'd guess it'd mean draining down the system cutting the pipe to unblock the coupling it back up ???

I also wandering how the water would run if i drain the rad again and with the central heating off unscrew the top of the lockshield .... would i get a jet of water shooting upwards until the whole system emptied or are they one way ?? ??

As you can probably tell i aint no CH engineer but prefer to do as much myself as i can.

My system as far a i can tell was installed in about 1988 with 8mm microbore, i'm not sure if the main feeds will be 15 or 22mm ??? and i have a Vaillant 828se boiler.
Ideally i'd be looking at changing a few more of my upstairs rads to double panel as when it was installed they didn't believe in placing them under windows so theres no convection effect with the cold air with them all fitted to internal walls.

Please don't knock me donw to much for not getting someone more knowledgable in to do it all
Thanks.

 

[kevplumb]

Also in 2005 i had a new boiler and asked to have the system powerflushed which they did and at the time i thought it was done correctly, but since have realised that the 50 or so minutes they connected it up for was nowhere near as long as it should be on for !

nuff said

if you are getting some flow to the rad try a dose of fernox ds 40

 

[Beanz08]

I've tried taking the given advice and putting sludge remover into the system but still don't seem to be getting any change in the situation.

When i drained the rad to put the chemical in i removed the blanking plug and poured water through to check for a blockage inside the rad to the return connector and it flowed fine so i am guessing that the inside of the new rad is not an issue.

I then tried opening the lockshield a bit as i was guessing there to be a blockage here yet water flowed out of it quite freely.

Since putting the sludge remover in and finding i had the same problem that i originally had where the TRV pipe heats up fairly quickly but then over 10 minutes or so only the trv side and top of that rad gets any heat at all and that i would say is only warm and not hot.

I then tried making my own return by opening the bleed whilst it was running and let a few hundered ml run out and found that this did in fact help heat the top of the rad a bit more.....i did then switch off and leave it for a while before adding some more water at the filling loop.

I've tried the system with all manner of different combination of radiators swtiched on and off to see if one might be causing the effect on the other with no luck and have also left the lockshield fully open with the TRV set to 6 to try forcing it through.

Does anyone have any suggestions before i have to call someone in please.

Many thanks

 

[MisterG]

Hi

I had a similar problem, replaced the old rad with a double with about 3 times the BTU and still no joy.

In the end I opend the lockshield valve almost completely, and turned down the lockshields in other rooms a bit, especially the room with the thermostat.

I think the rad in question must have been at the end of the circuit and didn't have enough time to heat up before the room stat kicked in.

It works fine now, I think I'll need to properly balance the system at some point.

If this works for you, you'll need to balance your system.

Hope this helps.

Cheers

G

 

[bengasman]

You could start with balancing the system.

 

[petit_pablo]

Try as chris said and balance the system. What happens to the problem radiator if all the other rads are switched off? Does it get hot? If its still the same then a blockage on the return is likely. You can try removing the radiator again and connecting a hose up to the return valve and blasting mains water up the return. The blockage will most likely be at the manifold.

 

[Beanz08]

Try as chris said and balance the system. What happens to the problem radiator if all the other rads are switched off? Does it get hot? If its still the same then a blockage on the return is likely. You can try removing the radiator again and connecting a hose up to the return valve and blasting mains water up the return. The blockage will most likely be at the manifold.

Cheers guys.

Petit_pablo thats almost identical advice as i just from a plumber friend of my dads, basically told me to connect a hose to the return and open up the lockshield then hold the pressure with the boiler topup for a while and hopefully anything that may be blocking it will get flushed out.

Gonna try it over the next couple of days and i'll put the pipe into a bucket so i can see if any solder or similar comes out.

To the other guys, i think it is gonna be a blockage as i;ve had every other rad closed off completely and the CH on with just this one fully open and still get the same results.

Thanks all !

 

[petit_pablo]

Petit_pablo thats almost identical advice as i just from a plumber friend of my dads, basically told me to connect a hose to the return and open up the lockshield then hold the pressure with the boiler topup for a while and hopefully anything that may be blocking it will get flushed out.

Gonna try it over the next couple of days and i'll put the pipe into a bucket so i can see if any solder or similar comes out.

To the other guys, i think it is gonna be a blockage as i;ve had every other rad closed off completely and the CH on with just this one fully open and still get the same results.

Thanks all !

Do it the other way round. Put a hose & the bucket under the flow valve and open that then fire mains into the return so its heading back towards the boiler. \if its blocked at the manifold u want to push it out not further down the pipe.

Do you pipes go back into wall or under floor?

 

[Beanz08]

Petit_pablo thats almost identical advice as i just from a plumber friend of my dads, basically told me to connect a hose to the return and open up the lockshield then hold the pressure with the boiler topup for a while and hopefully anything that may be blocking it will get flushed out.

Gonna try it over the next couple of days and i'll put the pipe into a bucket so i can see if any solder or similar comes out.

To the other guys, i think it is gonna be a blockage as i;ve had every other rad closed off completely and the CH on with just this one fully open and still get the same results.

Thanks all !

Do it the other way round. Put a hose & the bucket under the flow valve and open that then fire mains into the return so its heading back towards the boiler. \if its blocked at the manifold u want to push it out not further down the pipe.

Do you pipes go back into wall or under floor?

Under the floor in the bedrooms, from there it feeds the whole house.

So are you saying i should link the flow to the return with a pipe then open that up so its just a straight run of mains water ?? Bit confusing for a diy'er

 

[petit_pablo]

Under the floor in the bedrooms, from there it feeds the whole house.

So are you saying i should link the flow to the return with a pipe then open that up so its just a straight run of mains water ?? Bit confusing for a diy'er

Nooo Garden hose onto return and hose to outside / bucket on flow.

 

[Beanz08]

Under the floor in the bedrooms, from there it feeds the whole house.

So are you saying i should link the flow to the return with a pipe then open that up so its just a straight run of mains water ?? Bit confusing for a diy'er

Nooo Garden hose onto return and hose to outside / bucket on flow.

ok so last time then ....
the garden hose is feeding water into the return - yeah ?
then the flow is basically flowing water through itself and out of the system via the hose... so far so good
i take it i still need to be topping up the system from the filler loop to keep water in it ?

Thanks for your advice, i'll leave you to it now

 

[petit_pablo]

ok so last time then ....
the garden hose is feeding water into the return - yeah ?
then the flow is basically flowing water through itself and out of the system via the hose... so far so good
i take it i still need to be topping up the system from the filler loop to keep water in it ?

Thanks for your advice, i'll leave you to it now

No need to have the fill valve open too just remeber to turn boiler off 1st! The system will end up drained down but shouldnt cause you much grief to refill