CH/HW Problems

[wigg]

I have a fully pumped open vented system with a Baxi solo boiler & a grundfoss 15/50 pump and a holywell 3 position valve. I have had this problem for the last couple of years but it always rights itself except this time.When the central heating is on only there is no problem, its only when the hot water is called for that after about an hour the system starts making really loud noises, it sounds like its going to blow up, and the water in the expansion tank gets hot. When the hot water is timed off but the heating is still on the heating then fails to operate. To get the heating working again I have to bleed the rad in the bathroom as this becomes full of air and the 2 vents either side of the pump. I have just fitted a new pump and 3 way valve but the problem still occurs. At present the heating is working perfectly but I have to heat the hot water using the electric imersion heater, the problem has got to be in the hot water circuit, this is doing my head in have you any ideas. Thanks - Wigg

 

[twgas]

I'm thinking you've got system design fault, probably in airing cupboard, which leads to air ingress, corrosion and sludge.

a clean with sentinel X400 would be a good start.

 

[wigg]

Thanks for the reply Mick. Being though the central heating works fine on its own would you just clean the dhw circuit. The system is about 15 years old (i should of said) and for the previous 12 years there have been no problems.