Radiator problem - sludge or broken?

[spursfan323]

Boiler and cylinder fitted 2 years ago along with 3 rads downstairs and ++some++ pipework replaced - also 9 old rads left, so 12 altogether

Even with CH thermostat up to high, all the new ones only get hot at the top third or so - but the old ones are all fine

(Also, the flow pipe on the 1.8m gets boiling hot but the return only lukewarm/cold)

I've heard of sludge but to me it sounds strange that only the new ones have sludge, so it just possible that they are a bit broken? (builder was the type to cut corners/costs where poss)

Thanks

 

[RoughWaters]

The only sensible answer is that the new rads are a much more efficient at transferring heat (probably convectors) and the old rads (probably pannels) are much less efficient at transfering heat so they are warmer to the touch. You have answered your own question by saying the return to these is cooler. Bet the return pipework from the old rads is hotter because they are less efficient as dissipating heat. Ask yourself is the room actually cold?

 

[JohnD]

turn off the hottest ones. Do the others then heat up?

Then read up on "radiator balancing"

(That is a much more "sensible answer" )

 

[Armo74]

Agree with john, if it hasn't been done already and the rads heat up when the others are turned off it could do with a good dose of balancing

 

[45yearsagasman]

The only sensible answer is

That is a bold statement to make when there could be many reasons why those rads are not heating correctly. Lack of balancing is the first thing to check and also how these new rads were connected to the existing circuits.

 

[misterdubya]

The only sensible answer is that the new rads are a much more efficient at transferring heat (probably convectors) and the old rads (probably pannels) are much less efficient at transfering heat so they are warmer to the touch. You have answered your own question by saying the return to these is cooler. Bet the return pipework from the old rads is hotter because they are less efficient as dissipating heat. Ask yourself is the room actually cold?

You serious?

 

[I Like Sleeping]

Are the lockshield valves on the returns open or mostly shut?

 

[Agile]

It rather sounds as if the builder has used undersized piping on the new rads. The rule of thumb is a maximum of about 3-4 kW on a single 15 mm supply.

It may well be possible to correct the problem by careful balancing!

The motto of this story is not to use a builder when a heating engineer is needed.

Tony

 

[spursfan323]

It rather sounds as if the builder has used undersized piping on the new rads. The rule of thumb is a maximum of about 3-4 kW on a single 15 mm supply.

It may well be possible to correct the problem by careful balancing!

The motto of this story is not to use a builder when a heating engineer is needed.

Tony

I too suspected this. I only wish I had known these before taking on the contractor. (This was only one of a number of things he messed up). Tony - I'm in NW London as I believe you are - would you be able to visit and advise (if it would be beneficial)? I'm sick of trying to balance the system without getting it right (i am a bit of a perfectionist) and it would be a shame to waste more time if a Pro could identify a different reason why the rads arent heating properly.

In answer to the other responses:

1. Roughwaters: The new ones are indeed convectors and IMO the rooms are not as hot as they should be

2. JohnD: I've been trying to balance these damn things for ages, with varying success. At the moment its basically balanced in that the flow pipes gets really hot, so IMO if the rads were in perfect order I cant see why they wouldnt get hot throughout

3. trimster: LS are mostly open (although on 2 of the 3 it is actually TRV's, not LS's, but I have opened them as I would have for LS's)

 

[I Like Sleeping]

More specifically, are the valves on the opposite side to the trvs open?
Do the rads get warmer in heating only mode?
Have you tried shutting off all other rads apart from those not getting hot?

 

[Agile]

Depending on how the new rads have been piped, all I can say is that proper balancing can only make it better.

How much better depends on just how badly undersized the pipework is.

Anyone who wants a visit needs to contact me directly by phone or email.

Tony Glazier

 

[I Like Sleeping]

Sorry -no disrespect, you have to get to the route of the problem first. You can spend all day balancing to no avail if something else is wrong.

 

[Agile]

"route of the problem" ?

or

"root of the problem"?

 

[I Like Sleeping]

Not bothered, take your pick