Biasi 24S Combi - Hot Water problem

[Keith]

Hi

4 days ago, we moved into a new (to us, it was built in 1980) house.

It has a Biasi 24S combi boiler, which does the central heating, and the hot water.

The house is on 2 levels. The boiler is upstairs, behind a partition in the bathroom.

Upstairs has a bathroom, and an en-suite.

Downstairs is the kitchen.

The heating is fine, but the hot water is intermittent.

Opening a hot tap in the bathroom or en-suite results in cold water for

10 - 15 seconds.

The boiler fires up. The water then gets warm, sometimes even hot, but then the boiler turns itself off, and the water runs cold again. Occasionally, it does stay hot, but more usually goes cold again.

The shower in the bathroom is a mixer, and performs the same way as the hot taps.

The shower in the en-suite is an electric one, and stays hot: I assume this is because it heats water as it goes along?

The hot tap in the kitchen, while not fast, seems to keep the water hot.

The pressure out of the cold taps is huge.

The hot is coming out much more slowly. I'd estimate it would take

20-30 mins to run a bath.

What are the likely problems here?

The previous owner has the place covered by a service contract with Scottish Gas, and they are coming on Friday; but fore-warned is fore-armed, etc.

Cheers, Keith.

[Iain]

Hi Keith, Similar problem with my Biasi 28. Water runs hot and cold intermittently. I would be interested in hearing what the Scottish Gas chap suggested. Regards, Iain

[Keith]

Iain

The Scottish Gas guys came today.

They adjusted a valve to increase the flow rate, which solved one problem.

This also solved the other problem, i.e. the boiler not heating the water, This was because the flow rate was so low, the boiler didn't understand it was being asked for hot water.

When I asked them for their opinions on Biasi boilers in general, they were fairly scathing, and suggested that I should bedget for it's replacement in a few years time.

Cheers, Keith.

Ia> > Hi

[Agile Services]

The original poster seems to have a diverter valve which is starting to fail. The boiler should switch on with about 2.5 litres per minute flow.

The other posters have not given enough information but probably have blocked secondary heat exchangers. Run a hot basin tap and if the temperature gauge shows more than about 65 C then its partly blocked. This usualy cycles on off every 15-20 secs or so.

If the temp stays below 65 C then there might be a problem with the fan/venturi/aps. This cycles on/off much faster every 4-5 secs typically but needs a competent CORGI engineer.

These boilers are sold at a very reasonable price and are perfectly serviceable boilers but are bought by cowboys and the non registered and usually badly fitted without cleaning the system.

Tony Glazier

[Doctor Drivel]

This is a good point. BIASI are one of the better budget boilers. When fitted properly in a clean system they perform OK. I know of a few of these that have been in service for many years and not any problems at all. They use stock standard Italian boiler components. Having auto by-passes fitted and correctly set and the rest helps too. Also fitting a Magnaclean or Fernox Boioer Buddy filter on the CH return will protect the boiler together with inhibitor redosing every 4 or 5 years. All this applies to any other system too.

[Iain]

To give a little clearer understanding of my boiler problem: When any hot tap is turned on in the house, the temperature changes up and down continually. It gets hot for 10 seconds and then gradually cold for 10 seconds, then hot again. Any ideas?

Iain

[Guy King]

The message from "Iain" contains these words:

Sounds like insufficient flow. I would suspect the boiler is sensing the output temperature as too high and is shutting down - so the water runs cold and the boiler restarts - and so on.

Increase the flow somehow, by turning the temperature down or opening the tap wider.

[phil]

replying to Agile Services, phil wrote: Hi i have the same problem as hot water going cold every 5 - 10 seconds Electric actuator diverter valve gets very hot, when taken off and diverter pin on diverter valve pushed in it works fine . so is it the electric actuator a problem or diverter valve .There looks like there is a small weep of water from diverter valve pin .Thank you for your time .