I'm thinking of replacing my old Glow worm Space saver 60B MkII with a combi. I live in a smallish bungalow, there are only two of us, and we prefer to shower rather than fill the bath. If a combi is a good choice in this situation, what models would people recommend, for reliability in particular? I've so far only had recommended the Ferroli F30. The chap concerned says he's installed a lot of them and they've been reliable. He seems to think condensing boilers are less reliable and not worth the extra expense. Is this the case?
A combi could be a good choice for your requirements.
It is worth checking the water flow first, though. At the kitchen tap, time how long it takes to fill a container of known size and then calculate the flow rate in litres per minute.
If you are getting 20 or more, then you will be in good shape with water flow, If it's closer to 10 then the results could be disappointing. There are ways around this, though.
The performance of the Ferroli, from the specification is typical of a boiler of its size at around 12 litres per minute for a 35 degree raise of water temperature.
The efficiency is really poor. The SEDBUK database (UK seasonal efficiency) gives it a figure of 78%, which is the lowest that can be legally installed nowadays. From early next year, it would not be legal to install it as the effciiency minimum will be going up to 86%. In effect this will take non-condensing boilers, for the most part off the market.
Your installer may have good experience with the Ferroli product and it may well be a good data point. Certainly installers don't want unpaid call-backs.
Equally, don't forget that a lot of installers are quite conservative about newer technologies and with the WI groups of them that sometimes frequent heating merchants, stories and hearsay go around. Also, don't forget that manufacturers are not above doing marketing loyalty promotions with the trade in the form of a trip to Eyebyeza for every N boilers installed.
UK designed and made condensing boilers of earlier generation technology had a poor reputation because they were not designed and manufactured properly and used inappropriate materials.
Condensing technology has been in use in Germany and Holland for 15 years and the products are high quality. Increasingly you see designs and materials from these places.appearing in UK designed or made products as well.
If you trawl back through old threads here, you will read good things about Worcester Bosch and Vaillant products, but this doesn't eliminate others. I would avoid UK products of older designs. You can look at the SEDBUK database
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to see the date of first introduction of any product.
Mine isn't a combi, but I've had not a peep of a problem from my Worcester Bosch Greenstar HE28 System. They do a number of combi versions of this at various power levels up to 40kW, although you might find a 28kW more cost effective to run a single shower if you don't use the bath frequently.
Old wives' tale due to early poor designs released years ago. Modern condensing boilers are no less reliable than non-condensing types, although there are always some "lemon" makes, as in any field.
Just replaced an old Potterton indirect with a Vaillant combi (Turbomax plus
828E) Mains pressure is high and we get a torrent of hot water, provides an excellent shower. Conversion of the plumbing and removing the old cylinder was interesting, the original plumber had some strange ideas, but we managed to figure it all out. Had a couple of small problems, but both are resolved. The digital display stopped working after being on for a day, a Vaillant engineer swapped the display unit under warranty. The other problem was potentially more worrying as an o-ring was split on the mains water inlet filling loop valve. It must have been split when Vaillant manufactured the boiler and luckily decided to spring a leak while we were in, rather than wait until we were out, 17p for a replacement from the local diy shed. Luckily the boiler is very well designed and we were able to replace this in minutes. Looks as if a lot of thought has gone into the design so that it can be serviced easily.
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