COMBI BOILERS - RELIABILITY OF?

[geeveepee]

Very interesting discussion thank you to everyone for their input. Slight tangent re landlords but useful data just the same.
Like the man said we are not landlords. Everyone promises additional space becoming available - which is a consideration if you are tight for space eg flats etc - but we are not too badly off for space - kid's left home - I think. It is tempting but the honest truth is probably more space, more hoarding. More important is reliability. Further to the space thing we have noticed a lot of recent replacement combis being fitted in the roof space, is this just offering additional space downstairs or does it simplify or improve instalation? It does seem to mean a lot of exposed pipework.
We are (cue the violins) OAPs and don't want recurring breakdowns, expense etc. A lifetime guarantee (ours not the boilers) would be handy....
I noticed a report last week which suggested that one reason why modern boilers (just combis? not sure) are not producing the savings expected is that they are often not correctly commissioned when fitted.
To combi or not to combi?

 

[tryitandsee]

Again this tight Landlord is being bought into the equation. The choice of fitting a combi is mostly down to space, as new build flats do not have tank/cylinder space. Let alone enough room to swing a cat.

Agile, you mention the two items that are extra to the heat only boilers components, that being the diverter valve and secondary heat exchanger. If you search on this forum, both come 'up' with regular certainty as items that need repair/adjustment.

I know these boilers are a pet hate with me, but when you watch someone operate them, with no understanding of how they work, it makes you weep.
They turn on the hot tap and wait for the water to get hot, then start reducing the flow by turning the tap down, then it gets too hot and they turn it back up............and so it goes on. Meanwhile the boiler is trying to regulate its self trying to keep up. In effect, the operator of the tap is cocking up the design purpose of the boiler. Perhaps these boilers should be fitted with taps that are either on or off, with no adjustment for flow. They are not idiot proof and maybe that's the problem. [/quote]

 

[Agile]

Agile, you mention the two items that are extra to the heat only boilers components, that being the diverter valve and secondary heat exchanger. If you search on this forum, both come 'up' with regular certainty as items that need repair/adjustment.

The plate HE is the most common fault on combi boilers. But its not the boiler's fault. It is the cheap installer who has not power flushed the system. ( Usually a cheap third world installer chosen by the tight landlord! )

We charge £840 to fit a new combi PLUS the cost of the boiler. But we clean the system as required and give a full guarantee.

Many tight landlords pay less than £840 for the boiler and fitting!

The diverter valve on older boilers used to have a diaphragm which fails every 4-6 years. That should be replaced every 3-4 years on the annual service ( Whats that? ) but few people get theirs serviced.

Current diverters are motor driven and very reliable APART from the leaking pin shaft seal again caused by the dirty system boiler.

Older combi boilers did not control the water temperature very well but the latest are within +/-1 C although there is a little overshoot if the flow rate is changed too fast. However tenants just leave all knobs at maximum so that messes up the temperature of the hot water as it then varies according to flow rate.

Combi boilers are fine for the right application if they are properly installed and used.

Tony

 

[mickyg]

What would the trade fit in their own houses?

System boiler(vaillant 6 series) & stainless steel unvented cyl (take your pick of brands-vaillant, megaflo, range etc...)

just one opinion of course, but i guess this the question you really wanted answering

 

[Agile]

I know one person in the trade who has a 20 year old Netaheat boiler!

Its easy to spend other peoples money!

A better question would be what would you recommend for someone who wants the best with money not a problem. Many would say a Viessmann boiler and an unvented cylinder.

Tony

 

[namsag]

How can anyone say they charge 840 to fit a boiler when they have not seen what alterations are req ,What size gas pipe and the one they all forget. Where to run the condensate too. Also how many trvs or roomstat req and which type

 

[Corgigrouch]

What would the trade fit in their own houses?

I fitted a Bosch Worcester Greenstar 30Si In my house.. I wouldn't recommend what I wouldn't fit for myself.

 

[simond]

If you want the convenience of a combi but don't want a plate heat exchanger or a diverter valve then the ACV Heatmaster might float your boat.

It is expensive but simple, and condenses on hot water generation, which is unusual for a combi.

The reality is, it's not really a combi at all, it just appears to be one. It is more of a heat store, without the scaling up.......

 

[tonybhoy]

Had combi boilers,in my last three house, now for well over 16 years and really not had any real problems.

Current house is a 30s detached bungalow with a loft conversion ,two bathrooms with showers ,two teenagers and two adults. On average four showers and two baths a day 365 days a year. House is toasty hot in winter and hot water excellent.

Existing boiler is a carppy Sabre (Vokera) 35 HE (£549) just over two year old with a Honeywell CM 927 RF programmable roomstat. Gas costs £60 per month on DD and I'm in the West of Scotland.

Total myth this nonsense about combis being rubbish,especially for hot water, in the right house in the right location and with the right installation they are perfect.

Personally if I were fitting a new one (combi) now to replace the one above it would be a WB 42 CDi with the RF WB programmable roomstat although I do prefer the Honeywell one I have at present.

 

[simond]

I wouldn't recommend the worcester RF stat at all, your CMT927 is far superior to use, to look at, and more reliable.

 

[BigBurner]

If you want the convenience of a combi but don't want a plate heat exchanger or a diverter valve then the ACV Heatmaster might float your boat.

It is expensive but simple, and condenses on hot water generation, which is unusual for a combi.

The reality is, it's not really a combi at all, it just appears to be one. It is more of a heat store, without the scaling up.......

The Heatmaster is a combi as all is "combined " in one box. The Atmos has no plate heat exchanger or 3-way valve. Plates are not such a problem.

 

[BigBurner]

Had combi boilers,in my last three house, now for well over 16 years and really not had any real problems.

Current house is a 30s detached bungalow with a loft conversion ,two bathrooms with showers ,two teenagers and two adults. On average four showers and two baths a day 365 days a year. House is toasty hot in winter and hot water excellent.

Existing boiler is a carppy Sabre (Vokera) 35 HE (£549) just over two year old with a Honeywell CM 927 RF programmable roomstat. Gas costs £60 per month on DD and I'm in the West of Scotland.

Total myth this nonsense about combis being rubbish,especially for hot water, in the right house in the right location and with the right installation they are perfect.

Personally if I were fitting a new one (combi) now to replace the one above it would be a WB 42 CDi with the RF WB programmable roomstat although I do prefer the Honeywell one I have at present.

The Glow Worm 38CXI with outside weather compensator sensor and dedicated temperature sensor/programmer is a very good combi indeed. Make sure a Setinel, Spirovent or Magnaclean filter is fitted. The room sensor modulates the burner along with the outside sensor.

 

[BigBurner]

A twenty year old heat only boiler has very few parts to go wrong when compared to any modern boiler, combi or not so it is hardly surprising that they give very little trouble but the system still has a pump and motorised valves and thermostats.

..and they go wrong and when they do no one blames the boiler. Those components are inside a combi and when they go wrong they blame the boiler. What has to be assessed is the total system problems, not just the "boiler".

 

[tonybhoy]

I wouldn't recommend the worcester RF stat at all, your CMT927 is far superior to use, to look at, and more reliable.

I agree but by fitting a WB product it is covered under the warranty along with the boiler.

 

[tonybhoy]

.

Make sure a Setinel, Spirovent or Magnaclean filter is fitted. The room sensor modulates the burner along with the outside sensor.[/quote]

Fitted a magnaclean on a boiler replacement last week and the customer told me that BG's salesman said that only they are able to install them.

They must be getting desperate ,apparently the salesman was in the house for over two hours and ended up going down on his knees begging the customer for a £300 deposit cheque and a signature on the contract then he bugged her on the phone for the next few weeks.[/u]