Replacement gas boiler suggestions?

ActingDanClark

Ten years ago following construction of an extension had a wiesmann vitodens 100 fitted. Trouble from day one, frequent fault lights,water pressure insufficient almost daily necessitating the addition of a manual 'boost' and constant monitoring of pressure.
Tried different rgi technicians over the years but problems persist. The extension necessitated one extra radiator, but I've had the immersion separated from the system hoping to compensate. System is serviced annually.no evidence of leaks anywhere in the house.
Online research suggests this boiler is not wiesmanns finest creation- do I replace it and if so, what with?
System consists of 12 rads in a 2 storey house

DGOBS

If you are constantly topping up the water, you have a leak, and no boiler (or heating system) will not be affected by it, so getting to the bottom of that before you replace any boiler will be paramount.

iwillhtfu

We replaced ours last year with a Worcester bosch - pricey but very good I can't remember the model but it had all the bells and whistles gas flow regulator and other bits.

ActingDanClark

DGOBS wrote: »

If you are constantly topping up the water, you have a leak, and no boiler (or heating system) will not be affected by it, so getting to the bottom of that before you replace any boiler will be paramount.

Thanks, Wednesday it needed topping up, yesterday the pressure was too high!

DGOBS

Ok, if pressure is going over 3 bar, then you have an expansion issue (assuming your filling valve is not letting by) and you need to check if your getting water (when over 3 bar) out via the safety valve and dripping on the external pipe, as this could also be your water loss issue.

What happens is, you top your system to 1 bar, lets say, then the heating come on under full load, as the water in the system heats is expands, you have an expansion vessel to cope with this, but is the air side of the vessel is down on pressure, the water has nowhere to expand into, and the pressure gauge rises (it will rise normally only 1/2-1 bar, but more if the expansion charge is down) and when it exceeds 3bar, the safety valve on the boiler lifts to relieve the excess pressure (they are notorious for not reseating afterwards and dripping constantly), Then when the heating goes off and the water cools and contracts, the water pressure goes back below the initial 1bar, because you have lost some due to the safety valve operation, and end up with the low water pressure.

As above, check for signs of water loss via the safety valve pipe (usually external to the where your boiler is fitted)

ActingDanClark

Many thanks, I had the outlet sitting in s pint glass for months and the water level only reached 2 or 3 cm. I've had several gas technicians in and they all swear it's sorted.


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DGOBS wrote: »

Ok, if pressure is going over 3 bar, then you have an expansion issue (assuming your filling valve is not letting by) and you need to check if your getting water (when over 3 bar) out via the safety valve and dripping on the external pipe, as this could also be your water loss issue.

What happens is, you top your system to 1 bar, lets say, then the heating come on under full load, as the water in the system heats is expands, you have an expansion vessel to cope with this, but is the air side of the vessel is down on pressure, the water has nowhere to expand into, and the pressure gauge rises (it will rise normally only 1/2-1 bar, but more if the expansion charge is down) and when it exceeds 3bar, the safety valve on the boiler lifts to relieve the excess pressure (they are notorious for not reseating afterwards and dripping constantly), Then when the heating goes off and the water cools and contracts, the water pressure goes back below the initial 1bar, because you have lost some due to the safety valve operation, and end up with the low water pressure.

As above, check for signs of water loss via the safety valve pipe (usually external to the where your boiler is fitted)