Problem preventing pipe freeze in loft - help needed please!

[Robbiebob]

Can anyone help with this problem please? This year I suffered terrible water damage after pipes burst in the loft - and am keen to prevent happening again. I am quite new to trying to deal with this and have only just got the house back after lengthy repairs.

There are times when I am away from the house for days or weeks at a time. The loft is cold insulated and header and cold water storage is in there. I have joist level insulation and would prefer to leave heating on low when away to prevent other problems in the house (so draining down isn't a great option).

I have been advised to leave the loft door open to allow heat in from the house below. Won't this also be really expensive in fuel? Can I reduce this by also insulating at rafter level (thinking of thermawrap)?

There are no ridge level ventilators - can I leave a 25mm gap at eave level (between joist insulation and rafter insulation) instead? Will this allow sufficient circulation in the 50mm gap to prevent condensation? Would leaving the ventilation gap make the rafter insulation a waste of time with no benefit?

I'm dreading this winter

 

[Burnerman]

Its always a worry when a house is left unoccupied, but leaving the heating on is a great advantage.
Leaving the loft hatch just ajar will naturally allow heat to escape but I'd be thoroughly lagging the tanks from the top, using heavy insulation on the pipes and maybe using one of those tube heaters below the tank - 50 or 80W? After all, the loft doesn't need to be a sauna, just kept at 3 degrees or so.
Your loft insulation proposal sounds fine, so long as some air can circulate you can open things up in the Spring if you want.
Turn the water off, naturally - and you could drain the main water tank down a bit too if you want.
Don't forget to lag the expansion pipes that curve over the tank tops!
John

 

[mointainwalker]

It is standard practice not to insulate beneath any tanks in the loft to minimise risk of freezing, so first off remove any insulation there.


This is enough for most people, but if you are away for extended periods maybe you should also wrap the tanks in insulating blanket and finish off, if practical, by enclosing the space between the tanks and the ceiling ( if they are raised on frames) either with more blanket or pieces of solid polystyrene/PIR insulation.

Leaving the loft door open would be expensive and should not be necessary if you follow the steps above.

Obviously the house heating needs to be on at a low level because the above relies on heat bleeding through the ceiling to warm the tanks.

Forget insulating the rafters, you are simply wasting cash. The eaves should not be blocked with insulation so that wind can whistle through the soffits and keep everything nice and dry ( and cold, but only above the insulation )

 

[Robbiebob]

Thanks for all the support. I have thought about tube heaters and even looked at a few - will it be be safe to use in a loft? Is there any risk of fire? I'd also need to run a supply through the loft hatch - kind of worried about that too, though!

 

[Burnerman]

I fully appreciate your concerns!
I've never had a nasty failure with a tube heater but if I was using one I'd use the minimum fuse possible and connect it via a circuit breaker too. It could be used with an uncoiled extension lead.
I'd make sure the thing wasn't covered, but working in a free air area on the loft boards below the tank.
There's also the possibility of using 'space heating' as found on condensate pipes of combi boilers.
Wrapped around the pipe, they give just enough heat to prevent the condensate freezing. Maybe this could be used around your tanks - I don't know.
Is there someone who could keep a key for you, and check on things daily? After all, if your gas boiler packs in, you're back to square one.
John

 

[Symptoms]

Robbie - my advice if you're going away for a few days or weeks is to:
turn off water at stop cock
drain down cold water tank
... 10 minute job.
While you're at it shut the gas off at the meter.

Back in the day (mid 80s) I did what you're proposing (heating on low, hatch ajar, followed all rules re insulation, etc, etc) and came back from 10 days away for Xmas to total destruction. My insurance company (AA) told me it was the biggest domestic claim they had that year ... mind the reinstatement was brilliant but it took 8 months. I learnt my lesson ... I shut everything off and on return from any break it only takes 10 mins to turn stuff back on. Oh, and I always (as an extra messure) turn the water off in the street.

Call me paranoid if you like but I sleep easy when away.

 

[Robbiebob]

Thanks for the advice everyone.

I'm now thinking to reduce the size of the header tank and put it in the bathroom above the hot water tank. Then, remove the direct shower and install an electric shower. This may have the effect of reducing the water pressure in the system but not by much. After this I can remove the storage tank from the loft altogether. It'll be easier to shut off the water when I'm out to restart when I'm back... any thoughts or problems anyone can see?

 

[sharphead]

I almost had the same problem last year but managed to thaw the pipes with no leaks, the problem is it froze during one afternoon when the electricity went off and cut out the heating. I had the trap door open, seriously worried about this happening again the house was built in 2007 and seems to be extremely well ventilated in the loft. Would it be bad to roll out extra fibre glass over the eaves for the winter.