New Heat Exchanger - Seems less flow

macman

Your installer may be a Master Plumber, but is he (or was he) CORGI registered (or GSR if the install date was on or after 1/4/09)?
If not then he is breaking the law-regardless of his plumbing qualifications.

northernsoul

My gas usage when at max water temp was 0.641 over 10 min so 3.84m3 per hour which is in spec i think (nominal 4m3/hour, +5% 4.20, -10% 3.60), so i think it is ok.
Its good that i do not need a power flush!
The pipework is Hepworth Hcp2o and says barrier on it.
Directly under the Kitchen is the cellar where the pipework goes along the cellar ceiling to the Kitchen rads, the front room rads and up to the bedrooms through a partition. Hopefully the filter can be installed there.
Is it normal to have 15Ltrs per flow to the cold water tap, therefore presummably 15 to the boiler, yet only 9/10 Ltrs comes out of the hot taps. Does the boiler 'take' some of the flow rate away. The kitchen hot water tap (10 Litres/min flow) is below the boiler so no fighting against gravity there (if at all that makes any difference)
thanks

jalexa

northernsoul wrote: »

Is it normal to have 15Ltrs per flow to the cold water tap, therefore presummably 15 to the boiler, yet only 9/10 Ltrs comes out of the hot taps.

Given that the gas rate is "about right" I would agree the DHW is probably in spec. Bear in mind the output is not defined only in l/min but l/min at a specified temperature rise. For the 837 boiler its 15l/min at 35deg rise (or factory set at 12.6l/min at a 42deg rise according to the data sheet). IMHO plenty adequate for a good shower and will get better as the cold feed warms post winter.

northernsoul

Thanks for everyones help.
On a more general note records indicate May 2007 to May 08 with old boiler used 19800 KWhs. May 2011 to May 12 new boiler used 16400 KWhs (1441 cubic metres), saving approx £100 per year which is the same cost as my maintainence contract. Keep your old boiler as long as possible i say. Never had anything major wrong with old back boiler for first 20 years and lasted 24 in total.

Canucklehead

O.P.: has the primary heat exchanger been replaced or the DHW heat exchanger? Your boiler is underperforming on DHW....a competent RGI should be able to diagnose and treat what ails it.

Canucklehead

northernsoul

Hi Canucklehead
All it says on my homecare checklist is 'h/exchange'. I cannot recall the gas man specifying whether it is the primary heat exchanger or DHW heat exchanger, but as the noise only occured when using the hot water, i presumme it is the DHW.
As i said, i only, like suggested, counted how much gas the boiler used for supplying hot water for 10 min and then multiplied by 6. There may be some inaccuracy there, but if its worthwhile, I will contact British Gas and suggest it is underperforming.
Thanks