Combi Boiler - Performance Question

[Dan Robinson]

Too tired and inebriated to read that last post from the op due to the lack of paragraphs .... But, please don't hand over any money until after a GasSafe inspection.

Any bona fide installer would accept that as a condition of mediation.

However don't assume that what you can find things for online is what you expect the installer to charge you. Respectable installers might use material cost as a mechanism for offsetting base labour costs which makes their charging structure fairer on the more complicated jobs.

(this is all relative)

 

[CanYouHelpMe]

Too tired and inebriated to read that last post from the op due to the lack of paragraphs .... But, please don't hand over any money until after a GasSafe inspection.

Any bona fide installer would accept that as a condition of mediation.

However don't assume that what you can find things for online is what you expect the installer to charge you. Respectable installers might use material cost as a mechanism for offsetting base labour costs which makes their charging structure fairer on the more complicated jobs.

(this is all relative)

Sorry my message below was meant to be with ref to this - not very good at this!

 

[CanYouHelpMe]

Sure I hear what you are saying and figured that but the point of me paying him anything was to not leave him out of pocket on the materials while we get this sorted. He'll have lost earnings re the time spent here but he won't have paid anything for that....

Also at the moment I can't say I own the boiler as I have not paid for it

I said to hm I would pay for the cost of the boiler/materials, it was not his suggestion, he jumped at the chance and told me it was 1500 + VAT (on top of the what I have paid of £144). At this point I got wary he could walk away on that without too much pain but leave me with a right mess to sort out.

 

[dilalio]

It is meant to be the 30KW that is what he said it would be - it says 600 on it but a sticker on the top says 630 combi - tbh I am confused, the manuals cover all and I cannot see anything that tells me exactly what mine is

....Well it's not mine yet... things have gone a bit aggro today as I would not pay 2k for materials, I said they were at most 1k the whole bill is 3k and I think the remedial work I need done to fix what he has left me with will be close to or over 2k, I was going to pay the 1k as that seemed the right thing to do but I have been advised not to pay anything until we reach an agreement as to how this will be resolved, he won't talk to me until I pay 2k, I won't pay 2k as I kinda think I won't see him again and be left in a right pickle so we are at stalemate....

Yes they were gas safe registered although I am still not convinced the guy that did the installation is the guy on the register but that is another another matter (the boss came back and redid most of it). I have a gas safe inspection booked. I was waiting til the remedial work was done as did not want to antagonise the guys but seems too late for that now. It has been just short of a month I have no light in my kitchen, no usable shower, radiators that won't get hot (not due to the boiler but part of what he quoted to sort out but actually made worse) radiator valves that are now leaking (ok they do go but had they done the job as quoted probably would never have touched them and they would be ok, for now anyway) the exterior of my house looks like it was put together by toddlers (where they took out one flue and put in another). A builder (sent by the plumber) did come to take a look with a view to making good - I probably can't write what he said but he wouldn't touch it, I have dirty water from the heating system thrown over my conservatory, I have a very saggy kitchen ceiling that I have now been told probably contains asbestos so I have to go get that tested and possibly removed by specialists before a new ceiling and coving can go up and be painted, to top it all I have a boiler I am not convinced is up to the job.... He did initially make moves to sort out the disaster but the only thing he has done is put a copper pipe down he the ground outside my back door (clearly he agreed that vent was not safe), tilt the flue, wipe a bit of the conservatory down, tidy up the pipe work and make the electrics safe (but still not suitable for the electric shower he insisted was such a good idea) There was an electrician lined up but he stopped him coming out and I had heard nothing more about a builder or what will happen with the ceiling.... Hence my cause for concern.

It is obvious you are dissatisfied with the work that has been done. However, without a site visit (to inspect the works) or, at the very least, some photos posted here, showing the various issues, none of us here can determine how much of this situation is down to installer, and how much is down to customer! It is probably a bit of both, but does read, so far that your "awareness" has been heightened due to some glaring errors by the installer (ie flood damage).

Fortunately, you have handed no money over and should refrain from doing so until you have had it inspected by both Gas Safe and an alternative installer.

Once you have been advised, please make sure that you give the original installer the "opportunity" to put right what is necessary, according to any report before contracting others.

If they don't respond to your attempts to contact them, then you need to put in writing that unless you receive a response by a certain date, you will have no other option but to have this put right by others and all contractual obligations (ie money due) with the current installer, will be void.

You may also wish to advise them that you will be seeking reimbursement for extraneous remedial work that needs carrying out due to damage caused by their actions.

I am not in the legal profession and the above is just general advice on where you could go from this point. Have a chat with Cab or Trading Standards about how to proceed, but you do need to attempt to contact the current installers, stating your intentions.

Keep us posted. Be interested to hear how this goes.

 

[Hot&Cold]

no usable shower,

do the hot water taps issue hot water? The boiler has a built in flow regulator to provide constant hot water flow (say 12 lpm) the gas supply needs to be adequate to reach the required temperatures.
Maybe the shower (we dont know what item you are using as a so called shower) could be faulty,plumbed incorrectly or not suitable for your new combination boiler.
Getting the boiler and your system working correctly needs detailed onsite investigation and then correction Tbh should not be to much of a problem.

have you got the building regulation compliance certificate for the new boiler installation ?,the benchmark certificate should be filled out and the appliance warranty registered.

the water damage issues which occurred during installation need sorting out,seems you have given the installer the chance to rectify their issues. The installer/company will have liability insurance. Maybe ask your own property insurance their advice,sometimes legal cover is bundled into your insurance product.

its all sortable

H&C

 

[ianmcd]

your boiler is 30KW on hot water demand, the 630 means 6 is the model 30 KW, your flue is installed wrong and should have a run back to the boiler so that condensation within the flue runs back into the boiler and is drained through the condensate drain, sounds like your flow rate for hot water is set too high, or not actually set at all, it should be set at time of install to the rate that the boiler is set to heat, this can however be affected by seasonal temp differences in the incoming water temp but I dont think that this is your problem,you have a throw at the wall installation as we in the trade call it

 

[CanYouHelpMe]

Re the shower - they installed an electric shower for me (their suggestion) but I do not a have circuit for it, they wired it in using some cable from the old shower but the fuse just blows!

I don't know all the proper terms but get what should have been done and wasn't.

Perhaps this is where fault lies with me as someone suggested as i did not tell him there was no separate circuit for the shower. If a tradesman is telling me this is the best option and quoting me for the work I expect him to have checked out the current situation and taken this into account which it looked like he did as i took him round what i had before (a power shower) and provided him the installation manual for that so he could see exactly what it was. He wanted to know about the pipe work into it but never mentioned electric requirements would be different. Until he fitted it and I saw the issue it is not something I think I should have known??

I don't yet have the cert but I have called gas safe to check it has been registered and they have confirmed it has been - is this what you are referring to or is there something else I have missed?

I have spoken to cab and been advised all comms now need to be by recorded delivery email, they have advised that as he has been back once already I have no legal obligation to have him back. Given the tone of his emails and the lack of respect, skill, care and attention he has shown I would be uneasy having him back in the property.

I am drafting a letter this weekend which cab will check for me - hopefully then it will make sense and I can see a clear way forward as right now it just feels like a mess but as you say it's all sortable...

 

[vulcancontinental]

Combi's are usually oversized for the heating load, and often undersized for the hot water. This doesn't cause any unmanageable problems usually.

I know of one house where a 28kw combi is exactly right for the occupants - it'a a six bedroom Victorian detached with one bathroom and two occupants.

If there isn't an additional expansion vessel the 8 or 10 litre one in the boiler isn't exactly right for a system with 28KW of rads.

 

[mogget]

Yes they have problems with that every time they turn their upstairs rads on. Unfortunately they won't let anyone but British Gas touch the system or give them any advice as they're "the Gas Board".

 

[muggles]

Yes they have problems with that every time they turn their upstairs rads on. Unfortunately they won't let anyone but British Gas touch the system or give them any advice as they're "the Gas Board".

amazing how slow some people are to catch on. It's 32 years since they were privatised, and 22 years since they split the network side of the business off. And we wonder why people still don't know who Gas Safe are...

 

[mogget]

Yup, BT for the phone, Scottish and Southern for the electricity, and no internet because "there's all sorts of things on there". What can I say...

 

[fixitflav]

George's post is good and will provide the steady state efficiency of the boiler..

To find the overall efficiency one has to take into account the gas burnt during the transistion from the OFF state to the steady state



It is what happens in those few minutes that reduces the overall efficiency. During that time the heat exchanger(s) in the boiler are being heated before the water recieves any heat. When the water flow stops and the boiler shuts down that heat energy in the heat exchanger(s) will then be disipated via the flue and be lost. The more often the boiler is fired up and shut down the more these transitional losses will reduce the overall efficiency of the system

That's right, but the OP hasn't asked about efficiency, just about getting a decent flow of hot water.

 

[bernardgreen]

It is not what i was expecting and I am thinking the boiler is either defective or not powerful enough.

That's right, but the OP hasn't asked about efficiency, just about getting a decent flow of hot water.

Part of "getting a decent flow of hot water" is the efficiency of the boiler.

Say for exanple someone who is used to a 10kW electrical heater shower changes to a 20 kW combi. With twice the rated power they would expect to get a better shower.

That would be the case if the boiler was at least 50% efficient in using heat from the burnt gas to heat the water. Maybe the OP's boiler in not very efficient at heating DHW water.

Boiler efficiency figures seem to be the efficiency of combustion and not the overall efficiency of getting the heat produced by combustion into the water.

( this applies to all gas boilers )

 

[ianmcd]

Part of "getting a decent flow of hot water" is the efficiency of the boiler.

Say for exanple someone who is used to a 10kW electrical heater shower changes to a 20 kW combi. With twice the rated power they would expect to get a better shower.

That would be the case if the boiler was at least 50% efficient in using heat from the burnt gas to heat the water. Maybe the OP's boiler in not very efficient at heating DHW water.

Boiler efficiency figures seem to be the efficiency of combustion and not the overall efficiency of getting the heat produced by combustion into the water.

( this applies to all gas boilers )

you type some utter pish

 

[bernardgreen]

you type some utter pish

some marketing people publish utter pish.

and some installers install utter pish.