How is it that regardless of which type of Forum there is always on
Prat that always enjoys embarassing him/her self!!
Thanks for all of the help everybody
Andy
IMM Wrote:
> --
> Do you have any experience of how
> much lag I will receive from this
> type of boiler as opposed to a
> stored system, especially as I had
> intended to locate the boiler on a
> gable wall in the loft and the
> kitchen is one end of the bungalow
> and the bathroom the other!-
>
> You are going to have two lots of lags.
>
> If it's a combi with no form of hot
> water storage, then you have to
> wait for the heat exchanger to warm
> up. I'm not certain exactly how
> long that takes.
>
> With either arrangement, you will have
> the delay through the pipes.
> This is worse with 22mm than 15mm
> because there is more water volume.
> You can calculate it from the flow rate
> and then work out the pipe
> lengths, treating them as a cylinder.
> (pi x r^2 x length) This can be quite a while.....
>
> One way round it is to use 15mm for
> longer runs as long as you can get
> the flow rate you need.-
>
> Some combi's have a heat exchanger
> pre-heat or an integral small storage
> vessel to reduce the lag to that of a
> normal cylinder with the same length
> of hot water draw-off.
>
> You can install a secondary circulation
> pump on combi, to keep the draw-off
> pipe hot all the time.
>
> Fit a secondary circulation loop back
> to the combi's inlet with a dedicated
> pump, or a normal CH bronze pump
> if more pressure is required to operate the
> combi's burner. Most modern combi's
> will operate at low pressures these
> days. Check valves must be used to
> prevent the pump pumping down the mains.
> This is similar to a secondary circulation loop
> on a heat bank. Before the
> combi, the inlet must be a length of 28mm,
> preferably two in parallel. being
> a part of the secondary circulation loop,
> this stores hot water that will also prevent
> a cold spot when the combi is going through
> the firing proving sequence. The
> draw-off/secondary loop must be well lagged
>
> Have a pipe stat on the loop near the
> boiler to keep the draw-off temp to
> around 40C, so it will not be extracting
> heat from the combi continuously.-
>
> Just to add. On the combi secondary circulation loop you can have a > many 15
> litre electric storage heaters as you like (distributed storage), > common
> item which can be had for around £60 or so. Hot draw-off from th > combi
> into the cold feed of the 15 litre heater, hot outlet of heater to col > feed
> of next (in series).
>
> - Haeraters can be under sinks
> - A couple on the back wall of the airing cupboard taking little space > and
> also is, in a loft, etc.
> - Have the taps on the pipe on the hot outlet of the heaters.
> - Have a pipes stats in parallel on the inlet to each (pipe stats ar > cheap)
> - Instant response at the taps,
> - As much storage as you want scattered around the house at convenient > points. >
> If drawing off a bath all the hot water stored in each will end up i > the
> bath a they are all in series (in line in the draw-off pipe.). So > one
> under the sink, one under basin, two in the back of airing cupboard > one in
> the ulitility room, etc. 5 of them gives 75 litres unvented, no tank > in
> loft, high pressure storage for around £300, which is DIYable. Whe > water
> is drawn off the combi and the stored water is used instantly, al > combined.
> When the 15 litre tanks are exhausted the pipe states keep th
> secondary
> circulation loop on, and the tanks are charged up again.
>
> If the combi is down then turn on the electric supply to them all > giving > backup --
AndyHingston