Cold radiator/slow to warm up - tried everything (bleeding, balancing, sludge etc)

[Martyn Allen]

Hi all

We moved into a new house last summer and when it came to winter we realised that the Kitchen rad had problems. Its the largest radiator in our system (1.8 mtr vertical double) and takes at least 1.5 hours to get warm, and then its only warm with spots/areas which are colder/warmer etc.

I have tried everything i can think of but nothing has made any difference. I have bled the whole system for air, removed the radiator and flushed for sludge (none - water was very clean) and also removed both the TRV and needle valve, cleaned reassembled, and also tried balancing the whole system - in fact i have also isolated every other radiator in the system and switched the heating on - this did make a slight improvement to the kitchen rad but it still takes over 1.5 hours to get warm and still has cold spots, but never gets really hot.

I have (i think) an S plan system as i have two Honeywell motorised valves in the upstairs airing cupboard. I have checked the heating valve and this looks - as far as i can tell to be ok.

The only thing that i can think of is that there is not enough flow to the kitchen radiator? - although the boiler is also located in the kitchen the cupboard with the hotwater tank and the S- plan valve and plumbing is located upstairs on the far side of the house - so i am assuming that the kitchen rad is actually the last one on the system as its the furthest from the diverter valve?

Also the Grunfoss pump located in the upstairs airing cupboard does not seem to be plumbed into the central heating line, but rather the hot water line? (but it only comes on when the heating is switched on?) - the only thing that i can think of is that this is used to help get hot water to the downstairs kitchen taps quicker? if this is the case shouldn't my system also have a similar pump located in the airing cupboard but plumed into the central heating line?

I have attached a photo for reference below:



What am i missing? any help is appreciated as we cant go another Winter with the kitchen being so cold again

Many thanks

Martyn

 

[oilboffin]

Get a plumber and get your system flushed

 

[Martyn Allen]

Thanks - but why?

I have already taken 2/3 radiators off and flushed them myself and there was no sign of sludge and the water was very clear.

 

[oldbuffer]

1. Hard to make out which valves are on which circuit, and whether the pump is only on the hot water. However, if other radiators get hot likely to be OK.
2. If its a vertical "designer" radiator, many of then have to be connected the right way round. There's likely to be a baffle plate just behind one of the four connections, designed to force the water round the radiator. This should be connected to the flow, and if its not the radiator won't heat up properly. There's sometimes a label or other marker stuck to the body near this connection.
3. If the pipework from the pump to this radiator is of some length, it may not be allowing sufficient hot water through to fully heat the radiator. Check to see if it is all 15mm. If less, then that could be the problem. If 22mm should not be the issue, but if all 15mm would depend on distance.
4. Try and map out the flow from the pump to the various radiators. Its possible that when the extension was built the new radiator was connected outside the flow of the pump.

 

[D_Hailsham]

Whoever installed the pump hasn't bothered to read the installation instructions which show that it must be installed with the shaft horizontal.

Installed as it is - shaft vertical - may have have caused irrepairable damage to the pump, which could be the cause of your problem.

 

[Agile]

Are the correct tubes in the rad heating up as the makers expect?

Many need the flow on a particular side.

We recently read on this forum of someone who put his in upside down!

 

[Martyn Allen]

Thanks all for the input, its appreciated - i forgot to mention that i also checked the orientation of the rads - they do have a diaphragm which should be located at the bottom when they are fitted, apart from that it does not make a difference which is the inlet and which is the outlet.

One of the areas which i cannot work out is regarding the pump pictured above - this is not plumbed into the heating circuit, only the hot water. If this is correct then the only central heating pump is the one located in the boiler - what are the circumstances that would mean an additional pump is also required? (like the above but plumbed into the heating circuit). I have tried to annotate the original photo which shows the flows.

A few years ago the previous owners moved the airing cupboard when they combined two of the bedrooms into one larger room -from what i understand this also meant changing to a pressurised tank a certain degree of re piping - is it possible that they may have plumed the pump incorrectly and this should in the central heating to provide more flow?

Thanks again guys

 

[D_Hailsham]

The pic was confusing me as it didn't make any sense- thanks for the explanation - though it still leaves some questions. A pic showing everything in the cupboard, so we can see what happens to the pipes which go out of view in your current pic, would be helpful.

What is the model no of the pump (Alpha 2 xxxxx)?

 

[Agile]

Thanks all for the input, its appreciated - i forgot to mention that i also checked the orientation of the rads - they do have a diaphragm which should be located at the bottom when they are fitted, apart from that it does not make a difference which is the inlet and which is the outlet.

Thanks again guys

That is not usually the case!

The usual scenario is that there is a restriction on the INLET side at the bottom between the first and second tube.

The effect of that is that it forces all the flow up the first tube to the top from where it flows down the others to the bottom and thence out to the return.

Does the first tube on the flow side get hotter than all the others?

Tony

 

[stem]

Whilst getting the radiators hotter is nice, I would be more concerned about the dangerous wiring.

 

[Martyn Allen]

thanks all - i have attached a load more pictures and also tried to sketch out the circuit diagram to try and help explain the set up i have - if we can understand what the Danfoss pump is doing or if it is incorrectly installed it would be a great box to tick. The model number is Alpha2 15-60 130

Also any help in explaining to me what the large red thing is and what it is for? - it looks like an expansion vessel of some description? (i guess that has just answered my own question?)

Agile: I dont think i was clear enough with my previous description, sorry - the rads have a sticker on the bottom which simply says 'Diaphragm' and a flow direction arrow - i have assumed that as long as the inlet and outlet correspond to this flow direction on the sticker they are installed correctly.

Again all input and help is really appreciated, many thanks

Martyn

 

[Agile]

Agile: I dont think i was clear enough with my previous description, sorry - the rads have a sticker on the bottom which simply says 'Diaphragm' and a flow direction arrow - i have assumed that as long as the inlet and outlet correspond to this flow direction on the sticker they are installed correctly.

Again all input and help is really appreciated, many thanks

Martyn

Well that would be expected to be the case.

But does the first pipe at the inlet side get hot?

And the others are rather cooler at the bottom?

Tony

 

[Agile]

I think your sketch is not quite right around the pump and filter!

 

[D_Hailsham]

thanks all - i have attached a load more pictures and also tried to sketch out the circuit diagram

The circuit diagram is attached OK; but where are the pics?

 

[Martyn Allen]

The pics are part of the pdf - you should be able to scroll down to see them?

Agile - i have checked again and i am sure my sketch is correct , though there are a few lines coming after the filter that go back to the cylinder and also another connection that disappears through the floor