Nearly New Combi Boiler Trade Ins -Any Market?

[bamberger]

This summer we had the CH changed from storage to combi with an Ideal Logic 35 + being installed . The noise from the central heating is awful –think of a roaring furnace. Following visits from the installer and manufacturer, it seems that the problem is putting a 2013 boiler onto a 1966 pipework system . The consensus from a variety of sources is that the problem might be solved if the pump speed could be turned down but on this boiler it can’t be adjusted .
I know I could go down the mis-selling legal route but frankly I’d rather cut my losses. I be grateful for opinions as to how much I might get for selling the boiler that retails (inc VAT) for about £950 and if I’m likely to be able to buy a similar boiler such as a Worcester Bosch that is also about eight months old but does have an adjustable pump speed. I can’t imagine that many boilers will come onto the market that are only a few months old.
The cost of installation included the necessary pipework in changing from storage to combi, removing the storage tank etc. Are combi boilers fairly universal fitting in that you take the old one off and put the new one in place without lots of costly pipework adjustments?
Thanks

[The Builder]

Swapping combis ........... while the final connections are (mostly) standard, positioning varies with each model. Making a few adjustments to the pipework is no big problem for any experienced plumber/boilerman, so I wouldn't worry too much about that.

Flue requirements can vary, but I would simply swap for a model that has roughly the same layout and requirements of the old one.

But ........... back to the plot.......... I'm surprised to come across a boiler with non-adjustable pump speed. Maybe that's the way they're going now?

Two things I can think of...

Pumps are often standard generic units (often Grunfoss). It should be possible to change the pump for an adjustable one. There's bound to be some work to do to achieve this. If it's too difficult or impossible within the boiler casing, then a pump can be sited externally quite easily. Moe or less any pump can be used then.

The other possibility is to simply fit some sort of speed controller to the pump's electrical supply. Rather like an extractor fan controller.

[bamberger]

Thanks for this .
Extract from email from Ideal "It is not possible to adjust the pump speed on any of our range of boilers as they are factory set to work at optimum provided that the boiler has been fitted in accordance with the manufactures instructions and industry standards."

How much do you reckon it would cost to supply and install an external pump and is it easy to bypass (or whatever you need to do) the existing pump?

Thanks

[The Builder]

//////"It is not possible to adjust the pump speed on any of our range of boilers as they are factory set to work at optimum provided that the boiler has been fitted in accordance with the manufactures instructions and industry standards." //////

Well, I've never been a great fan of Ideal. I think I'm even less of one now.
I guess the one-speed pump is a cheaper option for them.
They refer to "accordance with manufacturer's instructions...... etc! A neat get-out for them since I guess your system is, in some respects, non-standard by today's requirements.

If it were mine, I would still have a go at speed control. It's the cheaper option since we are not at all sure that pump speed is indeed the problem. That would need to be confirmed first.

Noise is so subjective. Difficult to comment without hearing it. Have you tried disconnecting the electrical connection to the pump when the boiler is in full swing? It may make no difference to the noise, which may well be with the burner/fan/flue arrangement.

I'll get to the other part of your reply in a minute.

[bamberger]

If it helps there is absolulely no noise when the system is just used for hot water. This suggests that there isn't a flue/burner/fan problem
A bypass was fitted in the garage where the boiler is situated by the installer in the hope that it would solve the problem . This reduced slightly the frequency of the noise in the house but made the garage noisy when previously there was no noise in the garage even when it was very noisy in the house.

[The Builder]

Well that does narrow it down a little. No fan/heat exchanger noise. Sounds like it's down to the vagaries of the pipework layout.

I don't know what the bypass was, but I'm guessing he was trying to relieve the pump pressure a little.

I would still like to see what happens to the noise when the pump is disconnected. This is pure quesswork of course. But, if excessive pump speed is the problem, you probably have two 22mm flow & returns rising from the boiler. These go to the rads. Very quick and easy to fit another pump in one of these. The existing pump would have to be disabled....... maybe even bypassed, but that should be possible.

The new pump could simply be powered from the mains and controlled directly from a roomstat.
Maybe powered and controlled from the original circuitry.

I'm just firing off ideas from the top of my head, bamberger. It all depends on the boiler. Its layout may well not be "forgiving" to alteration.

These are all just ideas for an experienced boilerman to try. This kind of thing is only resolved through investigation and experiment.

I wouldn't want you to commit to a different pump layout only for it to make little difference. Cost of pump plus fitting and alterations may be anything up to £200.

What you need is a guy who's willing to experiment. Most don't. They just work from the book.

I can only hope that our Hymie on this site sees this and responds. He knows way, way more than I in this field.

[Hymie]

'Hymie ...... knows way more than I in this field' - Oh no he doesn't; but I'll give you my two pennyworth anyway.


Although you can no longer buy old fashioned pumps, fitted with a conventional speed selector switch - modern smart pumps are available with speed control.
These smart pumps are expensive, take a look at Screwfix - their cheapest is £75 versus circa £35 for a conventional pump.

As The Builder says, virtually all standard central heating pumps are fitted with 1 1/2" BSP threaded connections at a set separation - therefore providing the pump body will fit within the available space (with the water flow in the correct direction), any pump should suffice.
Screwfix has a smart pump with a 6m head and seven speed settings (code 73917) for £129.99.

However to accommodate the pump within the confines of the boiler enclosure - many manufacturers opt for a bespoke pump with specially prepared fittings which mean it is not easily interchangeable. If such an arrangement is used in your boiler, replacing it will not be easy.
And from personal experience, swapping the pump head will not work.

Your cheapest option might be as The Builder suggests, fit a pump external to the boiler (powered and controlled from the original circuitry), but I would expect to pay closer to £250 given that around 1/2 of this cost will be the pump.

But before going to all this expense, The Builders suggestion of cutting the power to the pump (while the boiler is in full-swing) is a good idea – and should identify whether the pump is the culprit. But be prepared for the boiler to go into lock out due to the overheat stat operating.

[bamberger]

Thanks both of you . While it may not be the pump speed , it looks the likeliest culprit and how I wish I had bought a boiler with adjustable pump speed.

[Hymie]

The easiest method of disconnecting the pump (while the boiler is in full-swing) is to locate the electrical connector to the pump.
With the central heating on and the boiler having reached temperature (and switched off the main gas burner), pull the pump connector.

You will then be hearing the noise the system makes operational, but pumpless. Make sure you switch off the central heating before it calls for more heat - otherwise the overheat stat will operate.

[gness]

May I butt in here....hope you get sorted Bam...without too much expense.

I had a Combi boiler fitted in my 1960's house two years ago and it's as quiet as the grave.
My daughter has a house of the same age with a very noisy system which she is going to replace soon....mainly because it is so noisy.

In view of the problem Bam has had, the age of her house and wanting a quiet heating system what should she look for or avoid?

Hope you don't mind me adding on here, Bam.....you've highlighted a potential problem she didn't know about.

Gx

[Hymie]

Well, people are suggesting that having the ability to adjust the pump flow rate may help alleviate noise issues – so you could check that any proposed boiler has this facility.

However the new smart pumps are supposed to be energy efficient – and avoid the need for speed control. They work by sensing the system flow rate and automatically adjust the pump speed accordingly. So if you shut off a number of radiators in your home (or are controlled by TRV) – the pump will automatically sense this and adjust the pump speed/flow rate to compensate (saving energy).

[bamberger]

Final thoughts -would a power flush (system had a chemical flush) or new TRVs potentially make any difference?
If I do get an external pump fitted will it void the 7 year boiler warranty?

Thanks

[The Builder]

Bam, that's interesting stuff from Hymie about the self-controlling pumps. From that, I guess it could be that your pipework is restricting the flow, so making the pump work harder and creating noise.

A good chemical flush is normally enough. Powerflush usually for very old rads and pipework.

I guess you had no problem with the old conventional boiler?
Is your system minibore/microbore (8mm / 10mm pipework) ?
Are the rads original?

It may be the layout of the pipework. A very basic system might have been added to over the years. Branches and junctions may have been fitted in silly, flow-restricting places. There may now be "deadlegs" (remote rads branched off a run that is already at full capacity.)

I wouldn't even think of doing anything yet until you know for sure that it is the pump speed giving the problem.

I guess that any interference with the boiler would invalidate the warranty. Maybe an external pump could operate without bypassing the old one. I really don't know. It could be worth a try. At least, that way, there'll be no evidence of tampering except for the removed electrical connection which could always be re-instated.

[bamberger]

I disconnected the pump as Hymie suggested. No noise whatsoever!
No problem with old conventional boiler.
As far as I know the pipework and radiators are original so whatever pipework was used in 1966 is what will be there.
The remote pump sounds a good idea.
Thanks very much to you and Hymie.

[Hymie]

Although fitting an external pump will give you flow control – event at its lowest setting it could be noisy in your system, therefore a chemical flush might be a good idea before spending money on an external pump.

As with The Builder, I don’t know what effect on the system leaving the internal pump in circuit would have – it might restrict the flow too much for the external pump to cope, resulting in a failure to fix the issue.

One thing I would do is take a look at the model pump fitted in the boiler and contact the manufacturer; ask if they make an identical pump but with speed control.
If they do, you could simply swap the pump head out and voila – speed control with none of the potential issues with an external pump.

[Hymie]

As you are seriously considering fitting an external pump (with flow control) – if the dormant/redundant boiler pump restricts the system flow too much, you could take the pump head off and carefully remove its stationary driving impeller (which would be causing the restriction).

Although normally bonded to the motor shaft, it will invariably be made of plastic. So by carefully drilling multiple holes close to/around the shaft, the majority of the impeller could be removed. Alternatively you could have a blanking plate fabricated that seals the pump head orifice – thereby completely removing the restriction (and the pump from the boiler).