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By rikur_
#1649794
Bill McCarthy wrote:If you haven’t got one fitted, the next time you have the system drained / partially drained down, fit a Fernox magnetic filter. It has an attachment at the base of it for the addition of inhibitor / antifreeze. These treatments can then be added without further drain downs.
My filter - Fernox TF1 Omega Filter. The inhibitor is added via a pressurised disposable canister (with a fitting allowing it to be connected to the base of the filter unit).

I've got one, but that only seems to work for the addition of inhibitor, not anti-freeze. For full -11'c protection, I need to add 50l of antifreeze, albeit the reality is probably more like 20l for sensible north of england levels.
cockney steve wrote: Antifreeze will also lubricate valves, seals and pump. In the case of a power- failure , the one, isolated area of frozen installation, could potentially stop circulation in the whole system and repairing a burst pipe embedded in a concrete floor is not easy or cheap!

I guess the most vulnerable area in most modern boilers is the condenser radiator, as that is just inside the flue so close to being directly exposed to outside air temperatures, particularly if the wind is in the right direction. I suspect that isn't much difference between an internal or external boiler - but in an oil boiler there is far more water than the condenser in modern gas boilers, so should be less vulnerable to freezing.
Fortunately we don't have any concrete floors (suspended wooden floors) ... we did have a section of microbore freeze under the conservatory in Dec 2010 when we had a sustained period of sub -10'c .... but that was the same time that the water meters froze in the pavements.
I think I'd add a bit of anti-freeze to cover it for - 4'c or -5'c as a half way house.
#1649814
Mike Tango wrote:What difference does £100 make when added to the cost of having the new boiler fitted?


About a hundred quid?

:think:



:D
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By rikur_
#1649828
Mike Tango wrote:What difference does £100 make when added to the cost of having the new boiler fitted?

It would have been £300 if we'd had it put in straight away, as we've had to drain the system twice since it was installed to deal with an airlock and a failed TRV.
That's my main hesitation if I'm honest - £100 one-off wouldn't be too bad - but invariably we seem to need to drain the system every year to either move a radiator, extend the system, or deal with something that's broken (although the boiler is new, the rest is older, and suffers the common problem of an older house that's been rearranged and extended since the heating system was first designed)
By cockney steve
#1649837
^^^^^^^and that's a major issue and why I dislike the pressurised system. It's all very well and good saving fuel, but you spend it all on replacing leaking hardware, not to mention the inconvenience if you can't rectify and recharge the system yourself.
Drained water with inhibitor and antifreeze should be caught, saved and used to refill.

You can buy an awful lot of extra gas with the savings of continuing to use a perfectly-functioning atmospheric- pressure system.....note that a "Primatic" cylinder is not compatible with using an inhibitor/antifreeze.....if the DHW is served by a calorifier and there's a discrete makeup/expansion tank, you're good to go, no danger of contamination!
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By Flyin'Dutch'
#1649855
CS

Why do you think a closed/pressurised would leak more than an open system?

:scratch:

And >>95% of folks would not (be able to) repair or fix an open system any more than a closed one.

Before coming to the UK never experienced other than closed systems and they are just fine.
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By stevelup
#1649862
The boiler has a frost stat. There's no way any of the water in the heating system will ever drop anywhere near freezing unless you're going to leave the property for long periods of time with the power off.

I really wouldn't bother unless the above is the case.
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By cockney steve
#1649914
^^^^^^ thermostats fail! The very fact that it would, theoretically , never cycle in a constantly-powered system, means that an electro-mechanical one could seize up.
Solid-state also has it's problems. How many on this Forum , have CHT or EGT gauges? they are invariably thermistor- controlled and erratic operation or failure are certainly not unknown.

@Flyin'Dutch'

Probably the same reason the French plumbing is hard-soldered (brazed) the pipes tend to be smaller-bore,but much thicker walls the fittings tend to be more robust.

In short, English plumbing is pretty archaic and was never designed to be under constant pressure. It's now changing rapidly. Modern radiators are not only more robust, they also now invariably have large fin-areas on the back to increase their efficiency. Valves are sealed better, modern single-hole mixer-taps have adopted the Continental Microbore "tails" and flexible connectors are now common-place. We're moving forward, but slowly. I've intervened on 4 pressurised systems now, all suffering pressure-loss. the partisan loyalty of professionals hardly engenders confidence, either......One will categorically state Vaillant are carp, whilst another claims they're head and shoulders better than Worcester-Bosch.
I persuaded a friend with a 4-storey Edwardian house, to ignore the propaganda and not turf out her perfectly-functional "Glow-Worm" When an independent fitter was sent to assess for a safety-certificate, he confirmed that a new boiler would invariably lead to a complete new system.
Pre-war cars never suffered burst hoses and radiators as they do nowadays. The old thermo-syphon systems weren't pressurised and the odd pressurised ones were at ~5psi not the 15 psi or so of today's systems with their ultra light, thin radiators and pipework.
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By stevelup
#1649916
The frost stat in any boiler made in the past few decades is entirely software based and will use the multiple temperature sensors in the boiler to determine if it needs to fire. It's not a mechanical device.

Given that the OP is not leaving this property abandoned over a Siberian winter with the heating system shut down and no mains power, there is all but zero chance of any part of this system freezing up.
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By Flyin'Dutch'
#1649918
@cockney steve

The ultra-thin 8mm bore is something I hadn't encountered before coming to the UK either, as is the habit to fit radiators at random places in a houde on inside walls to keep the pipe runs short, rather than fitting them under windows as they should be. Funny lot you Brits!

@stevelup

I would not bother with anti-freeze in a system whereby everything was indoors, but an outside boiler is a different proposition. A power issue on a cold night with very moderate freezing temperatures can spoil a lot. I also understand the OP's boiler is oil rather than gas fired and in my experience oil fired boilers are more prone to failures than gas fired ones.
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By rikur_
#1649926
Flyin'Dutch' wrote:
I would not bother with anti-freeze in a system whereby everything was indoors, but an outside boiler is a different proposition. A power issue on a cold night with very moderate freezing temperatures can spoil a lot. I also understand the OP's boiler is oil rather than gas fired and in my experience oil fired boilers are more prone to failures than gas fired ones.

Different failure risks I think. Oil certainly does need to be maintained, filters, nozzles, etc .... and fuel tank contamination can be a problem (or even running out of oil) .... so in my experience of both, I'd say more likelihood that an oil boiler is going to be out of service for a week at some point than a gas one. That said, we've only had 2 days outage in 10 years (touch wood), and our Vaillant gas combi in the other house seems to have a few days outage every other year - but that's mostly been down to the combi complexities.

None of that should make the thermostat(s) any less robust, and I'd have thought even if the boiler doesn't fire, the pump kicking in and circulating the water around the system should stop any immediate overnight risk of freezing in typical uk temperatures.

I'm not sure how significant being external is (question as opposed to loaded question) - in any modern boiler, the condenser radiator is a few inches from being exposed to the outside world via the flue.
Oil boilers have large 'jackets' of water, rather than the small 'radiators' inside gas boilers, so a lot more water has to cool down and freeze. The boiler is also encased in kingspan type stuff, and I could imagine being somewhat more snug that those 'internal' boilers that sit in neighbours' drafty garages. At the moment (10'c outside) - the heating hasn't been on since 8.45am this morning, and the water temperature in the boiler jacket is still over 40'c.
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By defcribed
#1649934
Flyin'Dutch' wrote:Having the anti-freeze should mean that a boiler failure does not become a Central Heating disaster.


If you have a boiler failure and you're worried about pipes freezing then just drain the system down.
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By defcribed
#1649936
I've dealt with a number of plumbers (and systems) over the years but only have spoken with one plumber that I really trusted.

He said the following:

"If your existing boiler & system works and doesn't cost you much more than a service each year and the odd part here and there, then stick with it."

I think that's sound advice. Just how much more efficient is a new boiler? If it saves you £50 a year on your gas bill (will it even do that?) then it'd be around 20 years before it paid for itself. Hardly sound logic.

Apart from anything else, the sheer invasiveness of having major work done on the system will invariably lead to other problems appearing shortly after you're back up and running. Those of us who've collected an aeroplane from the engineers after major work will appreciate this point.

Heating systems are one thing that the "if it ain't broke don't fix it" mantra really applies to.
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By rikur_
#1649980
Flyin'Dutch' wrote:@cockney steve

The ultra-thin 8mm bore is something I hadn't encountered before coming to the UK either,

I must confess having originally been dismissive of it, assuming it was a lazy installation choice with no long term benefit .... but having one house now done entirely in 8mm/10mm plastic microbore and the other done with traditional 15mm/22mm, I definitely prefer microbore:
- radiators warm up much quicker as there is less volume in the system;
- balancing the system is far easier as every radiator on each floor comes direct from the manifold so you don't get issues with pressure drop to distant radiators via t pieces;
- I can lift the radiators off the wall and lie them on the floor whilst decorating without disconnecting nor draining (except the big ones!)
- I can isolate individual radiators from the manifold when disconnecting without draining the whole system
- The house isn't clogged up with intrusive fixed pipework that historically was always in the way of fitting a spot light, drain, or something else.
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