That time of the year again: Tube heaters for loft

[MM]

So far autumn temperatures are holding up well, but we might have a shockingly cold December like last year, so once again it will be a worry that the pipes in the loft will freeze.

So how about a tube heater? Are they safe to leave unattended? I read on Amazon that they have to be mounted on a wall, but there's no wall within feet of the pipes in question, so what would I mount one on? What wattage would I need for a smallish loft (2004-built 3-bed detached), 60W enough?

How about instead moving one of my oil-filled rads up there temporarily? I've got a baby one that even has a thermostat on (the tube heaters appear to need an extra thermostat).

MM

[Hugh - Was Invisible]

I have only ever had one pipe freeze. That was an elbow right in the eaves where the old sacking type insulation had evidently migrated away from the elbow over the years. It was in an exposed bungalow in Norfolk in an exceptionally cold winter some time between 78 and 83.

Our current house has 4 inches of loft insulation that have deteriorated/compacted over the years. I haven't increased the level of insulation with a view to avoiding freezing pipes while we are away. All pipes are reasonably insulated.

It is possible to get low wattage heating wire to put inside the insulation but I think this is more likely to be used in schools etc which are shut down over Xmas hols.

After this year we will probably be spending most of the winter in warmer climes. I intend to leave the heating on low and possibly the loft hatch slightly open in the winter. Not sure about the pipes under our wooden floored house?

[RJS]

Try this stuff:

proper pipe insulation.

Richard

[Andrew Gabriel]

I doubt a tube heater will do anything in a loft.

Make sure the pipework is insulated with the thicker-walled pipe insulation.

Make sure there isn't any insulation under the tank(s) and pipework (hopefully, the pipework is localised around the tank(s)).

If necessary, fit a froststat in the loft which brings on the normal central heating. (At least, that's what I've done.)

[Tim Watts]

Heating trace tape - around the pipe and under the insulation. Safe (if you don;t buy a crap tape - decent ones should be self regulating), inexpensiuve to run and fairly easy to install.

The wattage is low enough (10W/m ish) unless you have a silly amount of pipe.

Pop a cheap thermostat at the feed end to avoid running unnescessarily...

Here:

Watts

[Grimly Curmudgeon]

They certainly know how to charge for that. My local hardware/farmers' supply store has 18m kits for forty euros (inc vat).

[MM]

That sounds like it could be expensive. As I've mentioned before in this ng my house does not have any thermostat, even though it was built only 8 years ago. It just has Honeywell knob adjusters on all the rads. On the wall in the annexe next to the kitchen is the Danfoss timeswitch/controller at which I program heating and hot water independently of each other. So wiring in a froststat would have to be done by a heating engineer, I should think.

MM

[Brian Gaff]

I do a good deal in old chunks of asbestos.. grin...

Brian

[Andrew Gabriel]

One grandmother died in 1995, and it took a couple of years to sell the house. I left the heating on low and the loft hatch part open so some of the heat went up there. Water was turned off, so if something did go wrong, damage was limited to a tank full of water. Topped up the CH header tank from the cold water storage tank a few times, bailing the water with an old saucepan. If I'd know it was going to take this long, might have drained the whole water system instead. The next owners ripped it all out anyway, except the radiator pipework (the rest was mainly iron).

If you leave the loft hatch open, you need to check it's not causing condensation up there. If the house is unoccupied and ventilated, it shouldn't.

When we did eventually turn the water back on, I found the plastic guts of one of the tank ball valves had been damaged by freezing, so it didn't fully close anymore. As the water had been off at the time, it didn't matter.

[Paul D Smith]

Don't know whether you can get them here, but in the US they have "ribbon heater cable" specifically for this purpose. It looks not unlike those "light cables" except yellow and flat and you wrap it around all your pipes where it sits keeping them frost free.

Perhaps there's a market for them over here, if they're not available already.

Paul DS.

[The Other Mike]

How the hell did that get Buiiding Regs approval? Even the regs twenty years ago had something in about boiler interlocks when there is no call for heat.

[MM]

What has "boiler interlocks" got to do with a froststat and/or thermostat?

MM

[The Other Mike]

In basic terms you are not permitted to use the boiler thermostat to control the room temperature (previously you were)

You might possibly have a flow switch on the boiler in lieu of of a room thermostat in which case it is compliant.

[Hugh - Was Invisible]

Looks like it has TRVs. Do these make it compliant?

[Tim Watts]

They are - they've been mentioned at least twice in this thread - "heat trace cable"

[ARWadsworth]

YOU will call it heart attack cable when you see the price:-)

[Andrew Gabriel]

I don't think that's quite what you meant to say.

No, there has to be an interlock which stops the boiler firing and keeping the primary circuit hot when no rooms require heat.

I don't think this requirement is 20 years old though. My vague recollection is it may date back to the April 2002 Part L changes.

[MM]

What does an interlock look like?

All I have is the rads with the Honeywell TRVs and the Drayton program controller. The boiler (Wallstar 55 in the garage) has a knob on it to set the desired temperature, and two warning lights. There is nothing else.

House was built in 2004, along with 39 other similar properties.

MM

[gremlin_95]

Interlock means that when the room temperature has been achieved, the boiler is switched off until there is another call for heat. This can be achieved with a room thermostat wired correctly according to manufacturers instructions.

[Andrew Gabriel]

Most commonly, a room thermostat. But you can use any scheme that cuts the call for heat signal to the boiler when no heat is required. As someone mentioned, a flow switch in the radiator circuit would work, although you'd need to keep the pump on, or you wouldn't notice when a TRV opened. A flow switch working the opposite way around in the bypass loop would also work if the loop has a pressure differential bypass valve fitted.

I believe there are some intelligent pumps which might have some way to do this, but I've never looked at them.

There are probably loads of installations which don't comply. Heating installers are not all very good at keeping up with technology and regs, and there will be no BCO inspection as it will all be self-certified.