Radiators not heating up..

[gazzbo]

Hi There,
I was hoping one of you kind folks could enlighten me. I have a combi boiler system which is only 5 years old )Worcester Bosch 24i Junior) which works fine. I recently replaced a radiator in my kitchen as the radiators are getting on a bit (around 20 years). The problem I have is that the radiator will not heat up.

I have tried removing the radiator and flushing it through to check for a blockage, but its all clear. If I don't have the radiator connected (leaving the valves attached to the microbore) I can open them up and get hot water at pressure through the pipework. The return also appears unblocked as water under pressure can also escape from here when I open its valve. The radiator has been bled of air.

I have also tried closing the other radiators down, but again it makes no difference.

I have replaced a few radiators over the years but never come across this before.

Can anyone tell me what the problem may be? Just to let you know they are just standard valves on all radiators and no electronic wizardry.

Thanks in advance.

 

[Goldberg]

Is it just the new rad that doesn't heat up, or was the old one also cold?

What was the reason for replacing it?

How old is the house/pipework?

What gauge is the pipework?

Is the system dosed with a corrosion inhibitor?

 

[kevplumb]

how many kids do you have

does the wife work

is your gas bill high

do you have a downstairs loo

 

[gazzbo]

Is it just the new rad that doesn't heat up, or was the old one also cold?

What was the reason for replacing it?

How old is the house/pipework?

What gauge is the pipework?

Is the system dosed with a corrosion inhibitor?

Thanks for replying.

I replaced the radiator as it was around 20 years old and the wife wasn't happy that it didn't match the rest of the house. I should say that this radiator is in the dining room which was an extension to the house and bolted to the back of this is another room. This radiator has stopped working also.

The pipework is the same age as the radiator (it was all done before I bought the house.)

It did work prior to replacing (which really gets my goat!! Grrr)

Yes the system was dosed with inhibitor.

I have been reading LOTS and wondered if their may be a restricted flow at the minifold caused by some gunk which was left in the new radiator (I know, should have flushed it out before installing)?

Also I'm guessing the feed pressure should be higher than the return pressure in order to fill the radiator and then send the water in the right direction?

Thanks again.

 

[Goldberg]

Since you have two cold rads, it does sound like a distribution pipework blockage.

What colour was the water when you drained the system?

From the word minifold (manifold?) it sounds like you have microbore pipework - is that right?

The flow pressure won't be noticeably higher than the return when you open a rad valve, especially if the pump is off when you try it.

 

[gazzbo]

Yes it is the dreaded microbore. The water was clear with a slight tint (guessing thats the additive).

I was considering replacing the microbore from the manifold (sorry it was a typing error) back to both radiators, but obviously thats a last resort.

Do you think that would cure the problem... or am I clutching at the proverbial straw?

 

[Goldberg]

Yes it is the dreaded microbore. The water was clear with a slight tint (guessing thats the additive).

If it was like dilute urine then that's a good sign.

I was considering replacing the microbore from the manifold (sorry it was a typing error) back to both radiators, but obviously thats a last resort.

Do you think that would cure the problem... or am I clutching at the proverbial straw?

I don't think you're clutching at straws - if you've eliminated other possible causes then pipework excavation/replacement is the way to go. Is it plastic or copper?

Did you test the rad vents with the valves closed one-at-a-time?

 

[kevplumb]

if both rads are off one feed your wasting your time

if not try a bucket test

 

[gazzbo]

It's copper pipe and I have tried both valves one at a time using the vents.

Kevplumb: I take it you mean feed into one radiator and the return to feed of second radiator then return to main?

or am I imagining it wrong?

Thanks again to both of you.

 

[bengasman]

Untitled

• bengasman
• 7 Nov 2009
• 1

I can see..... I can see......

I can see it now. Clear picture it is; coldberk will miraculously come up with exactly the right solution after asking exactly the right questions.

How does he google it?

 

[gazzbo]

So is he right or wrong?

I'm still pulling at strings here?

 

[kevplumb]

one feed and it's teed to 2 rads

one return and its teed to 2 rads

did you try the bucket test ?

 

[gazzbo]

Not yet Kev, I'm off to the DIY store to get some pipe to try it. The Rads have seperate feeds but are from a main minifold.

 

[kevplumb]

you don't need pipe

drain and remove rad

open valves one at a time into a bucket and see what comes out

 

[gazzbo]

you don't need pipe

drain and remove rad

open valves one at a time into a bucket and see what comes out

Nothing but clear water now. There is descent pressure from both sides. When I hook it up the feed pipe gets good and hot but it can't seem to get to the return pipe. I thought it may have been a fault with the rad but I tried another and they both do the same. I have bled the rad but it still won't heat up.

Does this make any sense at all?????