On 06/04/2018 09:27, Harry Bloomfield wrote:
It happens that John Rumm formulated :
Did he flush the system carefully? (Like most HE boilers, they like a
nice clean primary system).

No, he was happy to accept that my system was reasonably clean, but I
had filled and flushed twice anyway. He didn't sound convinced that all
the obsession with flushing on a relatively clean well looked after
system was necessary.

No point in flushing a system that's basically clean. You just want to
avoid sticking a new HE boiler into one that has loads of crap
circulating, since modern heat exchangers are both easier to clog, and
also easier to erode with particulates circulating.

I did a thorough mains water flush on my system when I converted it from
vented to sealed and installed the new boiler - that was in about 2012

Probably did this article shortly after:

http://wiki.diyfaq.org.uk/index.php/...ating_flushing

Since then I have cleaned the TF1 out a few times and topped up the
inhibitor. Usually I have had about a teaspoon's worth of sludge
collected on the magnet. More recently after doing some pipework mods
and also swapped out a couple of rads for towel rads, plus quite a bit
of partial draining and refilling, there was a bit more sludge collected
- probably a couple of table spoon's worth. However the system still
seems pretty clean as you would expect.

Rather than the filter he had originally said he would fit, he fitted a
Fernox Omega TF1, because it could be installed in an horizontal or
vertical pipe. Horizontal suited the layout above the boiler better.

The TF1 also seems to be more robustly built/ all brass than the
Magnaclean he had originally suggested. It also seems a bit easier to
service it too. I gave it a clean after a few hours running - it had
managed to prevent some Plumbers Mait getting through to the boiler and
a tiny trace of magnetite.

Yup I used a TF1 on mine - although not the Omega... its worked well.

I have noticed a slight issue, that after a few years you need to torque
up the connections on to the (plastic) body of mine, and also the
service / drain valve, or else you get a slight weep from it. I was
wondering why I was getting a very slow loss of pressure, until I
noticed that the outside of my TF1 was looking a bit messy and felt a
bit "sticky" to the touch.

After the old Ideal was out on my drive, out of curiosity I gave that a
good forward and reverse flush through, to see what might come out of
it. There was nothing at all, clean as a whistle.

Whether due to the new boiler or the TRV's I have fitted, the whole
house seems to be much more evenly heated. I never bothered originally
to balance the rads and the poorly insulated and extended utility room,
with a too small rad, it always suffered from being less than adequate
heating. Probably due to other TRV's being satisfied, it now gets much
more heat pumped through to there.

It might also be the better modulation range on the new boiler -
allowing it to remain under the set point limit temp for a wider range
of load conditions. So you get longer less powerful burns, and less
overshoot etc.

I have ordered up a pipe stat, to fit on the flow. Intention is to set
that to 60C wired in series with the room stat, to limit the call for
the boiler to a 60C flow, so it stays condensing most of the time. I

Won't that just make for more cycling?

have had to set the main boiler stat to 75C, in order to get the HW tank
up to a sensible temperature. A luke warm 55 to 60C is no use to us and
the boiler only has the single flow temperature setting. With that
fitted, the boiler should stay in the efficient condensing temperature
range when just supplying CH, but be able to run hotter when water
heating is called for.

That's where controls like the VR470 come into their own... you can set
a fixed flow temp for the HW, and then leave the CH flow temp at the
whim of the outside temperature.


--
Cheers,

John.

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