Room slow to warm up

[gravies]

I've been having similar issues in a similar room and house. I'm seeing only 1 degree C rise per hour. E.g. 15C start to 18c in 3 hours with very mild 11C outside. Interestingly it takes about 10 hours to go back to 15C after the heating is switched off - so can't be entirely due to insulation?

• 
  Large radiator in bay window with single glazing.
  Heavy curtains in bay window but do not cover radiator.
  Wooden floors, above 3 foot cavity with air bricks and cellar.
  Old 1997 Ideal Mexico open flue boiler with h/w tank.
  Possible problem with boiler exit pipes being too narrow.
  Open system with filler tank in loft.
  Thermostat in hall - but setting to >30C doesn't help.
  12-feet high ceilings.
  Fireplace with gas fire - also struggles to heat the room.
  Radiator is too hot to hold when on.
  Recently flushed the radiator with a hose outside - lots of magnetic gunk removed.
  Each hour of heating uses about 1 unit of gas (4 bedroom house)
  Tried unscrewing lockshield valve to ensure flow to lounge radiator.
  Both out and back pipes in cellar are insulated with Climaflex.

Options to improve things as I see it:

• 
  Go with quote from BG to replace boiler with condensing model, fit magnetic filter, upgrade boiler pipework, powerflush system: £3,400!
  Install 100mm Kingspan insulation between joists under floorboards. ~£300.
  Fill any gaps for drafts under the skirting boards.
  Install radiator reflector behind radiators.
  Install carpet (not going to happen).
  Install SlimLite glass in the windows (still leaves top stained glass). ~£2k
  Replace radiator with larger / more modern version. ~£500?
  Install a second radiator. £?
  Just powerflush the system and hope this helps. ~£300
  Just fix the boiler plumbing. £?
  Try DIY cleaning with Fernox DS-40 (hard DIY with open system?)

Any other suggestions or comments very welcome!

 

[Agile]

How do you have a 3' gap as well as a cellar? Or is it a cellar for midgets.

Generally 50mm Kingspan would be adequate and cost effective. If you can put the Kinsgpan in whole sheets under the joists that will be more effective and a very easy DIY job. You could then puch fibreglass into the spaces too.

All the heat output questions would be best assessed if you can measure the flow and return temps at the boiler and major rads.

Whats the format of the house and the loft insulation?

Tony

 

[gravies]

Thanks Agile,

Understand your confusion on the cellar - half the house is cellar, the other half (under the lounge and dining room) is a 3-4 foot void with rubble.

Thanks for the tip about 50mm, I might go ahead with this but not looking forward to the many hours spend crawling around. My worry about Kingspan under the joists is that they won't be able to breathe; probably paranoid but that's what I've read.

House is semi-detached with ~20 mm of loft insulation (bottom layer is ancient but newer layer on top). I looked at adding an extra 15mm but not convinced at the moment.

I've tried to find a pipe thermometer to get the flow temps but nobody seems to stock them near me so will have to order. I guess the pro's use Infrared gadgets or just guess!?

 

[Agile]

I know that underfloor ventilation was always considered very important but I am not convinced its such a problem as long as it can breath upwards into the room.

Your thicknesses of loft insulation seem wrong. 200 mm perhaps?

We use a thermocouple sensor and meter specially designed for temperatures but Maplins often have reasonably prices multimeters with a "K" type thermocouple socket. The socket is two flat spade connects with one wider. The simple contact wire ended junction is sold seperately for under £5.

That type of sensor is particularly good for measuring room temperatures quickly as well as pipe temperatures.

The IR type have very limited use apart from identifying poor insulation on walls and ceilings. This results because they rely on thermal emissivity which can be very low compared with a matt black radiator.

Tony

 

[gravies]

Yes - 200mm, I occasionally get stuck in cm.

Thanks for the thermocouple tip; bought one of these and have a few readings.

Boiler exit pipe: 70C when boiler set to 6/6
Boiler return pipe: 65C

Radiator Lounge In: 70C
Radiator Lounge Out: 67C

Room Temperature: 17C
Outside Temperature: 16C

Not sure what is wrong with those numbers?

Other thoughts:

- The heat from lounge radiator in bay window may just be going straight up and out as the bay is single story and not insulated above.

- Heat from the room may just be going into the room above - wooden floors above too. No insulation between the ceiling joists.

- The radiators may not be radiating heat well as they have many layers of eggshell paint (not sure this can be the problem).

 

[Agile]

If only others would go and buy the test equipment and give us answers so quickly! Evidently a budding heating expert.

I and others will think about your ( severe ) problems in due course.

A minor point is that they system is designed for a boiler flow temperature of up to 82° but thats only needed when its -1° outside.

Another observation is that there is ( more than ) adequate flow through your boiler. If pump is on "3" then reduce to "2". The old boilers were designed for a flow/return differential of 11°.

In spite of their name, radiators give up well over 90% of their heat by convection and not radiation. Thats why we dont bother to paint them matt black.

Tony Glazier

 

[gravies]

Nothing better than a new gadget! Have to confess that I bought a fancy meter with infrared and thermocouple (wanted one for a long time... don't ask).

After lots of testing, it seems most likely that the bay window and the uninsulated ceiling are to blame. The ceiling above the radiator was reading 23C with a temperature gradient across to 20C opposite the bay window and down to 18C near the wooden floor. The floor of the room above was similarly warm.

To test the bay window theory I set up an angled 'deflector' above the radiator using a sheet of styrofoam. Temperature in the room started going up quite quickly and within 30 minutes was at 21C at sofa height.

To test the ceiling insulation I need to turn off the radiator in that room and see how warm the floor gets.

Unfortunately, these are not necessarily easy to fix! Would need to insulate the ceiling by taking up the floorboards in the room above (recently decorated), and somehow get into the cavity above the bay window and insulate.

Looks like it will be new jumpers all round for Christmas then!

 

[Agile]

Dont go insulating the ceiling as the room above uses the heat from the room below.

Certainly insulate the bay window if that has its own roof.

Then the windows, secondary glazing etc. Draught proofing etc.

Tony

 

[kevplumb]

Moderator 11
Moderator Comment Posted: November 4th 2010, 12:15 pm This message will expire on November 6th 2010, 12:15 pm Comment:
Please note rule 6 (Do not hi-jack posts.) - See here for the forum rules.

so try getting your finger out and sorting all the off topic posts out then

 

[gravies]

Update on this is that I have almost finished installing 120mm of Kingspan Thermafloor TF70 between the joists of the suspended floor. I've also started to seal the gaps under the skirting board with brown decorator caulk and have put radiator reflector on the wall.

I have graphs of the temperature rise and fall before and after and you can see an improvement, but it is not a 'night and day' difference. It still takes an hour to go up by 1C!

The Slimlite Glass has been vetoed so now I am back to whether or not I just need to suck it up and get a new boiler. However, since the radiators are at 70C and the boiler seems to be off most of the time, I'm not sure how this will help?

Am I missing something? Is the pump / room thermostat / loft insulation / something else to blame?