On Thu, 24 Jul 2008 07:12:28 -0700 (PDT), cynic
wrote:

He is an opportunist ******* posing as a salesman! The case in
question was an electric immersion heater with a one stage (failed on)
thermostat. The tenants ignored the bubling and banging (were they
deaf or simple?)

As it happens I occasionally hear the odd bubble first thing in the
morning when we use Economy seven to heat the water. The immersion
heater is set to 60C. Is an odd bubble ok or does it mean the
thermostat is a bit iffy?

The header tank was not fully supported but rather
balanced on two joists so it sagged and split pouring boiling water
onto the ceiling which softened and collapsed with a cot beneath it.

I would have thought a plastic tank would melt at high temperature no
matter how it was supported but I can see that in that scenario, the
lack of support may have speeded things up. I am reassured that our
tank sits on a sheet of plywood over a number of joists.

The relative efficiency is another matter but if you had told us what
model you have it would have enabled us to estimate the likely
benefits.

It is a Mistral M1A. The manufacturer cannot find the serial number in
records for the last fifteen years, so they think it is 18-20 years
old. The manufacturer told me that the boiler would have been 65-70%
efficient when new but loses 1% per year so is now about 45-50%
efficient.

Of course, like the plumber, they have a commercial interest to sell
me a new one. Does the above ring true or does it sound a little
fishy?

When I bought oil last time (Jan 08) it was £400 for 1000L. I heard
someone bought 1000L recently for £800. The manufacturer (Mistral)
said that a new boiler would be 95% efficient and mine is 50%. Will my
old boiler will use twice as much oil (95/50=about 2) or is it not as
simple as comparing efficiencies?

If so, I was thinking that in three years the cost of a new boiler
(£1200) would equal the cost of the saved oil. Or are my maths wrong?

Oh and one last point -most plumbers have no idea about how an oil
boiler works!

I searched through the Yellow Pages to try and find an OFTEC one, so I
had hoped this chap knew more than most.