Plumber left me with luke warm radiator

[PhatEd]

Hi there.
I'm after some advice on some work that we have had done today in the house to replace a single panel radiator with a larger double panel one. The chap has been out, drained down the system, installed the new larger radiator and refilled the system. He then bled all the rads and left it for half an hour to get up to temp, but it wasn't really heating up. He said that there is probably air in the system and so closed all of the lock shield valves on the other rads in the house to force everything through this one new rad. He left it another 30 mins and this new radiator is only warm at the top and nearly cold at the bottom. He then said that it's not getting as hot as he would like but I need to leave it like that for a week to see if it improves and to call him back if it doesn't. He then tried telling me that the pump might need replacing as it might not be up to the job of the bigger radiator, but I really can't see that. It's only one radiator that has been replaced (single to double Type 21)...

Obviously I've done some investigation online since being told this and from what I am reading it doesn't seem right. It sounds like there is an airlock in the system that needs sorting out? I have since contacted him this evening to say I'm not happy and to ask him to advise / come back to sort it and he has told me that an airlock can take time to clear and to see how it goes over the next few days.

Does this sound right? Or am I being fobbed off here? As far as I was concerned, this new radiator should have been fitted and in a fully working state before he disappeared. If there is an airlock, it should have been sorted out as part of the job?

Any advice appreciated.
Thanks

 

[centralheatking]

Hi. The pump speed is set to 3. It's not a combi, we have a boiler in the kitchen downstairs and a hot water tank in the airing cupboard upstairs. There are two smaller tanks above it for setting the pressure. He set it to 2 bar when he refilled it.
[automerge]1579520432[/automerge]

Hi. Yes he fitted new valves and TRV. It is a branded one from B&Q. Kudox Type 21 double plus Panel radiator White, (H)600mm (W)1600mm. The one it replaced was single panel (H)450mm (W)1100mm.
[automerge]1579520533[/automerge]

Ah ok no probs.
I did respond re the pipe diameter. Can't see you asking anywhere about the heating flow and rad sizes etc.
The pipe is 6-7mm plastic push fit piping that he extended with couplers to make it wide enough for the new rad. The new rad is this one Kudox Type 21 double plus Panel radiator White, (H)600mm (W)1600mm

I think that the pipe ..plastic push fit is too narrow to serve this radiator, let’s see what the others think.
Centralheatking That rad will be about 2.5kw or more I think 15mm copper would just about cope providing its got no other rads off it and goes back to the 22mm circuit. also plastic pipe has a thicker wall than copper so the inside is further restricted. I tried these things out a few years ago in my last but one house, just to see.
Centralheatking

 

[EvilDrPorkChop]

Do pipes come out of wall in centre then come down to rad valves, they could have possibly kinked the pipe when they've refitted the radiator back on the wall....Also could be a blockage on one of the 10mm pipes.

As CHKing says, pipes could be undersized depending on length of the run of the 10mm from the main flow and returns. If you turn all the other rads off does it actually get hot, or still nothing?

 

[John.g]

Its hard to imagine that the new rad didn't heat up with all the others off which I think they were except air or kinked piping as above, The ID of the pipework obviously also makes a huge difference, for example if one assumes the rad as 2.5 kw at 75C/65C/50C then it will require a flow rate of 3.6 LPM and 6MM ID needs a diff head of ~ 1M/Meter, 8MM needs 0.25M/Meter and 10MM needs 0.08M/Meter, it would be interesting to know the actual ID of the above piping, all the plastic pipework in my house is ~ 10MM ID. ("1/2 ins OD")

 

[SJB060685]

John are you working off another spread sheet to calculate that? I've done a quick calculation and it doesn't quite add up, close but not quite the same

 

[John.g]

No, picked this up somewhere along the line so probably gives a reasonable estimation?

friction_loss

 

[SJB060685]

I was just going by my college texts books. To be honest there is very little in it so I shouldn't worry.
[automerge]1579552595[/automerge]
My text book only allows for copper pipe though and not what you linked so I've saved that link anyway to calculate for plastic pipe etc.
We were only out by .7 of a litre a minute and pressure was minimal difference

 

[Best]

Think in basic terminology, the original radiator might have been small enough for the microbore pipe runs to cope with the heat loss of the rad.
Replacing with new rad has perhaps x3 or x4 the output and pipes not adequate.
But circulating pump could also be part of the problem.
Over to the installer to take on the problem now, whether he is at fault or not.