Advise on old and install of new boiler

bwatt00

My boiler is letting out water outside and need to keep topping it up everytime i use it,i could get it fixed if i can get parts but as i think its near 20yrs old or more not sure,the plumber said the expansion vessel is probably the problem,would this be correct.
I asked if a big job and how old my boiler was,he said best i got a new one.

Now i know a place that i plan on getting one from but was wondering if anyone else could recommend any places so i can compare my price.
I am going i think to get a vokera combi 100,000 non condensing are these any good?And anyone tell be the best price around as i said i dont think the price i have now will not be more but who knows.

Also i asked for an approx cost on installing a new combi boiler of this sort and got a price and this is the second person thats quote the same amount,even when i have been told from workmates the prices they got there one done for etc was much less.
Whats the going rate for such job just so i know i am not being ripped off.

ALso as like most people you can get a company into do it and pay heaps,vat and all sorts of charges but say i wanted a cash in hand job,im being told it could not be stamped?Probably meaning if anything happened as to the home blowing up etc etc then insurance would not be interested,is this what it means and is it a good or bad thing,as like most people in this world we like trade guys to do jobs as cash in hand as it save a lot of money sometimes but would such job be wise and what could happen if i did.
And what would i gain doing it through the book,through a company etc

moneysavingplumber

If you are located in England or Wales you will have to have a condensing combi to comply with building regulation Part L. There are exceptions but it is highly unlikely you would qualify for that.

I would not advise having the job done on a 'cash' basis. It's worth remembering it is against the law if you are conspiring with somebody to defraud the Inland Revenue. Moreover, you are less likely to have a job done professionally and may invalidate the warranty on the appliance. The system will need to incorporate an automatic bypass, thermostatic radiator valves will need to be fitted on all radiators but the one closest to the room thermostat that you will also need to have fitted, along with a timer control for the central heating. The system will need to be chemically cleansed and treated in accordance with manufacturer's instructions and the Benchmark record will need to be filled in correctly and signed, and the installation should be registered with building control via Corgi.


Vokera Linea Condensing combi + flue= £ 700
Timer = £ 25
TRVs x 5 = £ 30
wireless room stat = £ 80
Injectible chemicals = £ 40
tube, fittings, plastics etc = £ 40
Electrician = £ 100
Labour = £ 360
Contingent = £ 25

Total= £1400

That's just a rough example, but the circumstances may vary greatly meaning differences in price.

alanobrien

Personally i would not touch a Vokera with a large pole.
We had one once........never again.

I would go for Vaillant, or Worcester Bosch and i am now hearing good things about Alpha who are giving 3 yrs guarentee on their boilers.

All the above use stainless steel heat exchangers which is something you should be looking for in a boiler given your new one will almost certainly be condensing.

john-306

alanobrien wrote:

Personally i would not touch a Vokera with a large pole.
We had one once........never again.

I would go for Vaillant, or Worcester Bosch and i am now hearing good things about Alpha who are giving 3 yrs guarentee on their boilers.

All the above use stainless steel heat exchangers which is something you should be looking for in a boiler given your new one will almost certainly be condensing.

Not stainless steel heat exchanger for the Bosch Greenstar range I'm afraid, they are all Aluminium/Silicon Heat Exchangers,
http://www.worcester-bosch.co.uk/index.php?fuseaction=product.detail&con_id=5067&detail_id=5176

dunno if that means you shouldn't be looking at Worcester Bosch then?
But I do know Glow-worm CXI range now use the stainless heat exchanger, but whether or not you add those to your list is debatable

gromituk

Aluminium/silicon? Sounds rather high-tech - could it be as good as stainless steel?

Back to the original problem: water is being lost through the safety valve. This is either because the safety valve is faulty (opening at too low a pressure or just leaking), or the pressure vessel is not taking up pressure evenly, so as soon as the water heats up, the pressure shoots up. Easy to tell which. As you top up the system, the pressure should rise steadily, rather than suddenly, if the pressure vessel is OK. No water should leak out of the external pipe when the pressure is less than 3 bar, if the safety valve is OK. This assumes the gauge isn't fibbing!

Either component is available separately as a standard fitting. Can one not remove and blank off the affected part, and fit an external one? I converted my system to sealed by fitting a pressure vessel/safety valve/filling loop/gauge outside the boiler.

moneysavingplumber: do you have any advice on my perennial question about the noisiness of boilers? Mine is on a landing so needs to be quiet. The old Potterton Netaheat's clunk-click of gas valves is not quiet at all! But don't some of the new condensing ones sound like jet engines instead? It's something you don't seem to be able to get any information about.

moneysavingplumber

gromituk wrote:

moneysavingplumber: do you have any advice on my perennial question about the noisiness of boilers? Mine is on a landing so needs to be quiet. The old Potterton Netaheat's clunk-click of gas valves is not quiet at all! But don't some of the new condensing ones sound like jet engines instead? It's something you don't seem to be able to get any information about.

Netaheat?? I was fitting them as an apprentice when they were state-of-the-art! Great boilers, and its successor the Profile was great too, such a shame they followed that with the Suprima :mad: .

Talking of the Suprima, some of them have the noisiest fans.

The Alpha CD13/18/24R condensing range are incredibly quiet, the first time I fitted one I had to check through the glass that it was actually lit, but sure enough it was.

Kettling noise in boilers is often caused by limescale build-up (despite the system being correctly treated with a suitable inhibitor) due to undersizing of primary flow and return pipe work, a classic mistake on boilers like the Suprima and Baxi Solo where the tappings on the models at 60,000 btu and over remain at 22mm but they should be immediately uprated to 28mm, so many plumbers don't bother for the obvious reason of cost and the fact that 28mm is less easy to work with.

Personally I wouldn't touch any condensing boiler with an aluminium heat exchanger, I mentioned the Vokera because the OP expressed a preference for one, but it wouldn't ever be on my list of recommendeds.

I was surprised myself when I did my research a while ago to find the Worcester Greenstars have aluminium exchangers, but they do. It's between Alpha and Vaillant for me I'm afraid, my preference definitely being the Alphas.

gromituk

Thank you very much for your advice - that's a good lead.

Yes, the Netaheat Electronic was installed when the house had central heating put in in 1984. I moved in in 1995 to discover its flue was discharging into the garage!! Admittedly the garage had a doorway-sized opening at the back, but even so I wasn't impressed. This might explain why the fan motor rubber mountings had hardened a bit and it was transmitting a lot of hum into the wall. Since I gave them a good massage there's been no trouble.

I moved the boiler upstairs, converting to a sealed system to reduce kettling, and for all the other advantages. I managed to obtain the essential overheat stat but didn't bother shelling out on a pump overrun kit, so once a year or so the overheat stat trips. I wanted to fit an air separator but hadn't heard of these being used on sealed systems, with an automatic (ha ha) air vent. I'm glad I did though - they're amazing. I see some of the Alpha boilers have one "upside down" to separate crud rather than air.

Whenever I've rearranged bits of the heating I've always put in larger radiators, in anticipation of the lower flow temperature a condensing boiler in condensing mode will produce.

When I change the boiler I'm toying with the idea of getting a solar cylinder and putting some panels on the south-facing roof. A lot to think about there - which cylinder, flat-plate panels or vacuum tubes, etc. I can't use an unvented cylinder - my mains water supply isn't good enough.

Pity you can't download PDFs for the Alpha boilers you mention. They don't have modulating burners, but I wonder if that makes any practical difference to efficiency? The 24S does, but it says that's only for unvented cylinders - I'm not sure why.

A friend installed a Keston condensing boiler a few years ago. That one's quite noisy, apparently.

moneysavingplumber

gromituk wrote:

Pity you can't download PDFs for the Alpha boilers you mention. They don't have modulating burners, but I wonder if that makes any practical difference to efficiency? The 24S does, but it says that's only for unvented cylinders - I'm not sure why.

A friend installed a Keston condensing boiler a few years ago. That one's quite noisy, apparently.

Kestons are a little dated now, but are one of the few domestic condensing boilers that modulate up to 40 KW, and they approve a working gas pressure as low as 18 mbar, which was handy on one of my installations where the initial working pressure on commissioning was only 13 (!!), and after Transco replaced the 20m long 3/4" main (!!!) still only managed to creep to 18. After Keston's approval, the Transco engineer signed it off as acceptable.

moneysavingplumber

gromituk wrote:

I can't use an unvented cylinder - my mains water supply isn't good enough.

Have you looked into replacing your main? Moling technology makes it far less disruptive (and it should be far cheaper if using an honest contractor) than it used to be. I do have concerns about the amount of 50mm plastic mains being thrust into houses when much of the the supply network is still only 100mm, but a 32mm, or even 25mm, blue poly main should give you adequate pressure provided the boundary stopcock and the spigot from the main to your stopcock is renewed.

gromituk

I haven't thought about replacing the main, no, but I upgraded the cylinder feed to 28mm and have separate cold feeds for the two showers downstairs, so there's no interaction and I'm happy with the pressure on all except the upstairs basin taps, which I cope with. I'm also on a water meter in the pavement, so that would need replacing, which would doubtless cost a fortune, and probably incur a higher standing charge as well.

gromituk

The SEDBUK rating for the Alpha CD24S (modulating 5.3-25.4kW) is 90.8% and the CD18R (fixed 18kW) is 90.1% - there's not much in it.