Biazi 28SM/C HE Combi Boiler hot water problem

[pdgtips]

I have a Biazi 28SM/C HE Combi Boiler. The heating system is excellent but the hot water is the total opposite. I have had the boiler since April 2010. The plumber said that the hot water temperature is restricted as the pipe work coming from the boiler is 15mm and then connects into a 28mm which is existing.
The plumber said that we need to take the old 28mm and change it for 15mm from the boiler to the bath and the sink basin.
I have changed 2 metres of pipe from 28mm to a new 15mm but then had connect back to the existing 28mm as this goes in to an area I cannot get to (about 12”). From this it then reduces for another 2 metres to 22mm. After changing this it’s made very little difference to the temperature coming out of the bath tap.
If I close the hot water tap so its only flowing about a third of its capability it’s very hot which would unfortunately would take an hour to run a good bath and the miss’s moan’s and wishes we had our old boiler and tank back.
If I run the shower which is a mixer shower from the top of the taps it’s so hot it burns my hands.
Do you think I need to change as much of the 22mm to 15mm which would leave about 18” of 28mm and 22mm which I cannot change or will this be a waste of time?

Many Thanks
PG Tips

 

[Agile]

Both you and your plumber seem to misunderstand the problem.

The size of pipe is related to the amount of cold water to be ejected before hot reaches the taps.

The large pipe loses more heat too. All hot water supply pipe should be insulated but rarely is.

At this time of year your boiler can only heat about 9 litres per minute of hot water. Set your bath tap to that and it will be fairly hot. Insulate the pipe and it will be hotter!

Tony