Advice on flow to radiators after new boiler

[Alan329]

Hi All, I am looking for a bit of advice. I am not a plumber, just a DIYer who has been doing his own plumbing for more than 40 years. I understand how central heating works with flow and return but have a bit of a potential issue which I want to discuss.

Bit of background first. I had a Worcester 35CDI fitted which was over 20 years old. It was still working very well apart from very occasionally it didn't recognise a hot tap being open and needing a reset to sort it, but it is in the kitchen and quite bulky. We are taking a wall out so I wanted a smaller boiler, also as it would be quite a job to change once the new kitchen is fitted, I thought it would be a good idea to fit a new one now and so save any future potential problems. I went for a Worcester 36CDI compact supplied and fitted by Boxt as it was much smaller but on paper was as powerful as the old one.

How it is installed: Radiators upstairs and down stairs. Flow is tee'd into a pipe which goes to the upstairs loop and the downstairs loop. Return starts upstairs, drops down a pipe to downstairs, runs all around the ground floor before returning to the boiler going through a Worcester filter just before the boiler.

The problem I am having is something I never noticed with the other boiler which is the lounge radiator is very slow to get hot taking much longer than all the other radiators. It is quite large (2400x400mm double) and probably on the end of the line, but other large radiators get hot much more quickly. All the lockshield valves are shut down to around 1/4 to 1/2 turn with the lounge radiator at 1 turn . I am wondering if the flow rate is less on the new boiler?

The upstairs radiators all get very hot very quickly, the downstairs all taking longer, but all are larger as less heat needed in the bedrooms. So I was wondering if it would help to reduce the flow to the upstairs loop, thereby diverting more to the downstairs. I can get easy access to the flow and return as it enters upstairs, so I was thinking maybe a 22mm gate valve on the flow that could be shut down to maybe half similar to how a locksheild valve works.

Any thoughts on whether this would be a good/bad idea? Sorry for the long post.

 

[SimonG]

Should you not be addressing this to boxt, after all they took your money!

 

[Alan329]

All Boxt did was supply and fit a boiler, they have not touched any radiators or any associated plumbing, so as long as the radiators do get hot why would they care? The lounge radiator does eventually get hot but it takes much longer than it used to

 

[Best]

The installers are responsible to balance your system as best as possible.
Putting a gate valve on one radiator circuit would be pointless as the rad valves on that circuit should balance those rads in relation to other circuits.
Gate valves are really only ideal for balancing a single pipe loop - say to a cylinder coil, where no other valves are there.

 

[SimonG]

Simply because sticking a boiler on the wall and connecting to it is not what I would define as a boiler installation.

System clean, controls, trv's, inhibitor, benchmark and ultimately the correct operation of the system. It's all required.

 

[Best]

All Boxt did was supply and fit a boiler, they have not touched any radiators or any associated plumbing, so as long as the radiators do get hot why would they care? The lounge radiator does eventually get hot but it takes much longer than it used to

They are responsible to have it working as best as it can be.
You said yourself that it worked with old boiler.
System was also supposed to be properly flushed.

 

[Scott_D]

Does the rad have a TRV?

 

[New Gas Engineer]

Did they powerflush your system before the boiler install?
Im only asking because you say all the upstairs rads get hot quick but the downstairs ones take longer.
Maybe draining the system down forced all the sludge down to sit in the downstairs rads?

 

[Alan329]

Thanks, I won't bother with that then. I may try shutting the locksheild valves down further but I think I will wait until it gets a bit colder as it is too hot to have the heating on.

 

[Alan329]

Yes there are TRV's on all but the bathroom radiator. All were fully open when I was testing .

 

[Riley]

All Boxt did was supply and fit a boiler, they have not touched any radiators or any associated plumbing, so as long as the radiators do get hot why would they care? The lounge radiator does eventually get hot but it takes much longer than it used to

They have not commissioned the system properly so the issue is very much there’s

 

[Scott_D]

Yes there are TRV's on all but the bathroom radiator. All were fully open when I was testing .

Try taking the head of that radiator
See if the pin moves freely

 

[Alan329]

They did a chemical flush but I don't think it was particularly effective for reasons I will explain. The pipe connecting the upstairs return loop to the ground floor return loop is right next to the boiler. The plumber decided to tee the boiler return to this upstairs return loop and downstairs return loop connected to the boiler at the tee. This may have not been too bad but as I explained earlier there is a return on the ground floor which is right at the end of the loop which has also got the Worcester sludge filter on. He tee'd this return into the ground floor return just before the tee where the 1st floor and ground floor return was tee'd into the boiler. I did point out that I thought this was wrong and very little of the return flow would actually go through the filter as half the ground floor and all the upper floor would not return through the filter. After he fired up the boiler and we found more than half the ground floor radiators were not getting very warm he drained the system and changed it back to the original configuration at which point the radiators got warm. He couldn't do a second chemical flush after this as he had no more chemical but he did add more corrosion inhibitor after I mentioned that there was no longer any in there. The big filters he used for the flush did collect some sludge, but far more was collected on my small filter after the system was run for 15 minutes showing the filter is now doing its job.

 

[Scott_D]

Any pictures?
I think you have found the problem with BOXT and other similar company’s
There is no survey and they only allow the fitters a set amount of time so it has to be ‘completed’ in a day then into the next.

 

[Alan329]

This is before the installation. The pipe furthest right is the return from 1st floor to ground floor. The pipe next it is the flow to first and ground floor which you can see is tee'd into the boiler (4th pipe from left) 5th pipe from left (with filling loop) is the return to the boiler

 

[Alan329]

This is how it is now

 

[Riley]

Pipework doesn’t tell us anything mate it’s one for the installer if they’ve not cleaned or commissioned the system properly

 

[Stu-B]

If it’s not right then get them back to put it right, or at least diagnose the issue.
Another set up where the big firm is creaming all the cash from jobs then sending some chancers to do the install.

 

[Ben-gee]

I don’t see how they can really recommend the correct system and give an installation quote without visiting the property?

Oh yes, by massively overcharging just in case and leaving you with “ a system” rather than the best system for you and your property I guess.