Anti-freeze in CH system?

[Nick]

A dumb question perhaps but I have a good reason for asking. My wife has inherited a house 280 miles distant which she visits about once a month. Fairly modern straightforward system. Gas (Calor) boiler with programmer & frost-stat, gravity DHW & pumped CH. Through the winter the boiler is programmed to heat for a few hours each day. Calor are supposed to top up the tank every month or so. The elderly neighbours, who live 1/2 mile away, keep an eye on the place for us. Gas ran out just before Christmas so we had to chase down there with several oil filled rads & time switches.

Draining and refilling the whole system regularly would be beyond my wife. I was thinking that if the CH was antifreezed it would be quite simple for her to switch off boiler & immersion, close mains water stopcock and drain DHW cylinder (thus dumping contents of storage tank as well). On next return reverse the process. She could cope with this.

The only pratfalls that I can think of are any effect anti-freeze might have on system components or copper and the propensity for anti-freeze to find potential leaks/weak spots. Is there something I haven't thought of?

Many thanks, and best wishes to all for 2010.

Nick.

[Usenet Nutter]

Personally I have not heard of "antifreeze" of any sort being added to a CH system but I'm sure others will say if they have . Usually systems have some sort of Frost setting or are set to come on at a preset low temperature using a programmable thermostat . Obviously you are concerned about burst pipes so could you not just drain down the system completely until the winter is over ...clearly we don't know what your wife's plans for the house are long term .

Why would you even be considering draining down and refilling every moth ?

[dom]

in mind the concentration required may make it quite expensive.

[mick]

The right stuff is Sentinel x500 inhibited antifreeze.

the programmer doesn't have a frost protection mode then I'd swap it for one that does, or parallel a frost protection stat across it. That way you don't need to set it to run at all. Many boilers will protect themselves, with their own frost stat, but that won't protect the house itself against burst pipes.

[The Natural Philosopher]

Not sure the anti-freeze wouldn't end up as gas in the system when hot.. I suppose it doesn't in the car..

If have had a rad freeze up on me once.

Thank god for Car Body filler.

Cant see that it would be anything but good for the copper work. Car rads/cylinder heads are, after all., primarily copper, and light alloy, and te stuff is saturated with corrosion inhibitor.

[Usenet Nutter]

Can't speak for car radiators being mainly copper but Cylinder Heads ??? That doesn't sound right .

[Cash]

Mick,

Surely no amount of 'stats' on the system will protect it against frost if there is no Calor gas in the tank to fuel the boiler? BTW, there is already a frost stat on the system. ;-)

Your "snipping" left out this important bit of information:

"Calor are supposed to top up the tank every month or so. The elderly neighbours, who live 1/2 mile away, keep an eye on the place for us. Gas ran out just before Christmas so we had to chase down there with several oil filled rads & time switches."

BTW, there is already a frost stat on the system. ;-)

Must have been a good party that you had last night. :D

Cash

[cynic]

Anti freeze for CH systems is most certainly available but your wife will have more problems than you think in draining the hot water cylinder. Much better to use a frost protection stat to protect all the pipes in the house. Being economical with the heating could just cost you a LOT more in rectification work later.

[Cash]

Ignore the typo error of BTW, there.... - I'm still recovering too! Bloody sore head. :-(

Cash

[David WE Roberts]

Intrigued now - how long does a tank full of Calor Gas last when the central heating is set to frost protection? Unless it is a very small tank and/or a very large house I would have expected a tank full to last all winter.

[Peter Parry]

You can't drain the HW cylinder by opening a tap, once the cold water tank is empty the flow stops but the HW tank remains full.

Why not leave the electric radiators in place and control them by their own thermostat set a degree or so lower than the main thermostat?

Keeping the house at about 10deg at all times isn't significantly more expensive than running everything on frost stats and helps prevent damp damage to carpets and furniture which can occur with prolonged cold temperatures.

[The Natural Philosopher]

those are generally these days aluminium alloy castings (light alloy). rads are still copper to the best of my knowledge.

[Nick]

From my op: drain DHW cylinder (thus dumping contents of storage tank as well)

Expensive and possibly dangerous given the usage of the property. By 'main thermostat' I presume you mean that controlling the CH. This works well, unless there is no fuel.

Agreed.

[Nick]

Thank you. I cannot answer your question and cannot vouch for the integrity of Calor personnel. The cylindical tank, installed by Calor to their specifications, is approx

1m in width/height x 1.5m long. It is a fairly large house, 4 bedrooms, remote and set on a Welsh hillside. Nick

[Dave Liquorice]

I was wondering when someone would say that. B-)

Yep, that seems the best solution to me. All the other suggestions of frost stats and firing the boiler etc don't work when the gas has run out. B-)

A slightly more technical solution would be a frost stat that started the pump running opened both HW and CH valves (or set a 3 way to both) and also turned on the immersion heater. That would stop the CH system freezing and may well put enough heat into the house to stop the domestic hot and cold supplies freezing as well.

[Adrian]

The Natural Philosopher gurgled happily, sounding much like they were saying:

Car rads?

No, plastic, pressed steel & ally.

[mick]

X~(

My point was that he should just leave it to the frost protection - no need to set the heating to run even for a few hours per day. That would save gas and, perhaps prevent the same problem occurring again. He didn't say *where* the frost stat is and it makes a big difference. There's no need to raise the inside temp to much above freezing to protect it (about

5C is ok). Doing so creates a big temperature difference with the outside and is very inefficient in terms of fuel usage.

...wish it had been a good party. I have to avoid booze & non-prescribed "fun" thingies (for medical reasons)!

[mick]

And me. It looks like he's using it *very* inefficiently.

[Nick]

Thank you. Please can you tell me what further problems we may encounter in draining the hot water cylinder. I am just trying to think about this problem logically and appreciate all sensible input. The plan, so far, would be to install a valve to drain the DHW cylinder. This valve remote from the cylinder and located close to the mains water stopcock. This valve also separate from the existing draincock situated on the cylinder. Remote drain would be piped to a nearby drain. By positioning the two close to each other, the task should be easier for my wife.

Frankly, it's bugral use using a frost stat if there is no fuel. As recently exampled.

Nick.

[Nick]

Thanks Mick, there is a frost stat in the system, see above. Unfortunately this is quite ineffective if there is no fuel to power the boiler. Nick