New boiler is fitted and working :-)

On the first day of the year that the air-con kicked-in in my car ...

Andy Burns presented the following explanation :

..and also the first day of this year, upon which I have seen a live fly.

Has the hood down today. But no flies. ;-)

How do you know? I just leave mine on auto. It does its stuff without notifying me.

Tim

The fan noise was sufficient notification ...

On the same day that I scraped the ice off the van windscreen in the morning!

Its not recommended to have your flies down while driving anyway ;-)

Did you go for the weather compensating controls? What about split temperature operation?

Did he flush the system carefully? (Like most HE boilers, they like a nice clean primary system).

It happens that John Rumm formulated :

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.

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.

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.

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 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.

When my new boiler (Ideal Logic combi) was installed over 4 years ago, it had 2 'power flushes' by the installer, and a magnet/filter fitted. I've drained and refilled (with inhibitor) it 3 times since, and still the water comes out black with a good few mm of sediment (I drain the system from the lowest point into a trug). Nothing on the filter at all. The black is almost oily - I've no idea what it is but must be coming from the original radiators (only 3/14 left now).

The system is potentially prone to blockages (6 of the rads take 10mm plastic pipe). All fine so far, but I'm wondering whether there's any preventative action I can take before the inevitable.

The obsession with power flushing etc on a system which worked OK before is merely a way of hyping up the costs.

It happens that Dave Plowman (News) formulated :

That was what my installer said and the way I too see it. There is always be some sediment in a system and some magnetite, no matter how frequently it is flushed out. Regular flushing and refilling will cause its own problems, in as much as the fresh water will have some air and oxygen in it initial+ly, which can cause some rusting until all the oxygen and air is out.

In the 30 plus years since the system was installed, I have never suffered a blockage. Poor flow to some ads due to lack of balance, but never a blockage or any sort of dirt come out of the system.

It sounds like air is getting in somewhere. No oxygen, no corrosion. You really don't want to change the water unless needed. As fresh water contains air.

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:

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.

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.

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.

Won't that just make for more cycling?

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.

John Rumm used his keyboard to write :

That is a possibility - but it depends on the hysteresis of the pipe stat. Its a bimetal type, but Danfoss don't spec. the hysteris, only the setable range. I'm hoping it will cycle no more than it would anyway, operating only on the room stat.

Its a Danfoss 041E0010.

since it stops the heating cycles sooner, more cycles are inevitable. Keeping the boiler in condensing mode is far more beneficial than the small downside of more cycling.

NT

Yep, maybe. Although the system doesn't need topping up as such - a couple of seconds on the topmost rad a couple of times a year. And there's absolutely nothing on the magnet.

It happens that snipped-for-privacy@gmail.com formulated :

New pipe stat arrived this am, fitted and it seems to be working. Vaillant do suggest the 418 boiler has anti-cycling built into the software.

At the moment, with it cutting the boiler off at around 60C, it is only doing a single burn in raising the ambient room temperature from 18C upto 22C - but outdoors is quite warm at the moment.

Early days, but - What appeared to happen, was the pipe stat cut the demand for the boiler off at 60C, heat from the rads continued to pass their heat into the rooms, then the room stat indicated its demand was satisfied, before pipe stat reclosed.