Radiator q's

Quatre Mains

Hello all
I have some q's around some heating issues I've been thinking about. My house is fairly cold most of the time. Its a concrete house , only a few years old (its in an estate)and has double glazing etc. There is insulating in the attic (tho I'm not sure what type/grade etc). It just seems to take ages to heat from the time I turn the heat on (oil), up to a couple of hours or so in some rooms.

1. are radiator covers helpful or a hinderence when it coems to heating a room? I like the look of them but I'm nervous about getting them in case it reduces the temp even further in the house.

2. Do those tinfoil things you can get in Woodies that you stick on the wall behin the rads really work?

3. In the sitting room the room is such that the only place I can put the couch is directly in front of the radiator. Any tips on how I can maximise the effect of that rad?

4. Can I buy better rads than the ones that came as standard in the gaff or are they much of a muchness?

5. Is it worth my while putting some kind of insulation on the underside of the roof or is that only really done when you're converting the attic?


- thanks folks, any other advice would be appreciated.

Cheers
Neil

delly

Only bit of advice i can give is regarding radiators.

Every radiator has a heat output which is referred to as BTU's (British thermal units). Whats meant to happen is you calculate how much BTU's you need for a room (HxWxL etc.) and get a radiator that fits accordingly. You also have to make sure that your heating unit can handle the total amount of BTU's your rad's produce, along with a bit extra for your hot water tank. I have a Potterton Suprima 70 (70,000 BTU's) and I have worked out my BTU count is around the 61,000 mark. If you do a search on the net you should find some calculators (B&Q have one on www.diy.com ).

If you know what make your radiators are, you might be able go to there website and work out the BTU count. My radiators are Myson so i went to http://www.myson.co.uk/premier.htm and downloaded a PDF file that gave me all the info. I recently replaced the rad in my living room based on these figures and it made a big difference. Other factors can also have an effect such as insulation, floor type, glass type and what direction your house is facing.

Hope this helps.

tcs

Would be interested in responses to pretty much all of Johnnycabs questions...

Do radiator cabinets block the heat?

If I've only 4 inches for insulation on attic floor but wanna put up some boards to store stuff up there, should I consider insulating underside of roof aswell/instead.

• Instead => will be heating virtually unused attic space.
• Aswell => more expensive but will get better overall level of insulation. Prob over the top.

Don't have much head clearance in attic so what are suggestions for insulation when joists only 10cm/4" and you wanna store stuff on top?

And what about the couch directly in front of the radiator? Know it's not ideal but when needs must, how do you ensure adequate heating?

Corkey123

I'd recommend increasing the insulation between the joists and flooring with chipboard. I would avoid the tongue and groove version just in case you have to lift it at some time in the future. Don't over fill the joists as this may put pressure on the ceiling and plasterwork below. Only you will know by examining the existing insulation and the room available for more.

Anything covering a radiator is acting as lagging and preventingc heat from radiating through the room. While radiator covers have ventilation they do restrict heat flow slightly, a couch in front of the radiator is similiar to a big lagging jacket.

rooferPete

Hi,

Insulation is a strange beast, you need at least 150 mm (6") preferably 200 mm (8") between the joists, what can also add to the insulation is the small pockets of air trapped between the fibres.

Maybe instead of crushing the insulation to the existing joist level you might look at cross lathing with 2" x 2" (44 mm x 44mm) laths screwed to the joists and then fit your floor for storage, one advantage is your floor could be strengthened by the closer supports.

The foil for behind the radiators does work when the radiators are on, a side effect can be they leave the walls cold which does away with any heat storage capacity there is in the walls.

To fit insulation between the rafters could cause more trouble than it solves unless you are using an insulation board because the heat that rises will meet the cold coming down from the roof underlay, that means at some point in the insulation you will have a "Dew Point" which can break down the isulation making it practically worthless.

I would recommend that you have you heating system looked at by a professional, your boiler may be too small for the load imposed or it could be as simple as the pump on the wrong setting.

In theory the couch shouldn't be as big a problem as it appears, the whole room should heat up, at worst the heat must get through the couch but once up to a comfortable level it should hold that level.

Sometimes heating problems can be caused by the way people use the system, not trying to be smart but it does happen, while some of the newer rads can let the heat out faster many of them do not hold any heat when the system is switched off.

I hope the above is of some help, if nothing else food for thought .

.

delly

rooferPete wrote:

or it could be as simple as the pump on the wrong setting.

Speaking of this, i recently switched my pump from the top setting of 65 to the middle setting of 46 because the noise at the higher setting was very loud. The heat flow at the new setting is fine and i can't see any loss of heat, but i'm just wondering is there any other effects that i'm not aware of such as extra pressure on the system?

patrido

yes, radiator cabinets resist the flow of heat, and will reduce the ability of the rad to heat the room.

yes, tin foil will stop heat loss by radiation through the wall. by the way, the heat storing capacity (thermal mass) of plasterboard is pretty small (especially the patch behind a rad), so don't worry about losing that you could always put a concrete block somewhere in the room to make up for it .

However, even if you do install the tinfoil... in a living space in a roof, the walls are not where most of the heat is lost, so they will not have a huge impact. heat is lost from your room in the following order (excluding windows and doors).
- the horizontal ceiling
- the pitched/sloped ceiling
- walls
- floors.
so prioritise insulation in that order.

The couch will resist heat to some extent (it will stop heat radiating directly into the room, and it will restrict the returning convection currents), but I wouldn't lose any sleep over it. The other things mentioned have a much greater effect.

Regarding Radiators...
if you really need it, you can buy rads with a bigger output. they are generally just a bit bigger. Any plumber or plumbing supplier will calculate what rad you need for a given size of room, and you can go for the next size up, and put a TRV on it to regulate the heat. However, not all rooms are the same, and if you contact a manufacturer (like barlo/quinn or myson) they will do a more detailed calculation for your room. It will take into account the u-values (how much insulation you've got), number of windows, external walls/surfaces, direction the room faces, etc.

Regarding insulation between the rafters...
- you must leave a ventilation gap of 2 inches above the insulation to allow air to circulate.
- compressing fibreglass into a smaller space reduces the effectiveness of the insulation and is a waste of money. if you have 4 inches of space (allowing for ventilation), only put in 4 inches of insulation. If you want better performance, put in better insulation (like xtratherm xt/pr or kingspan tp10).

Regarding condensation... there is always a condensation risk with insulation between or under ventilated rafters, but this can be overcome by carefully choosing your insulation, and the appropriate use of a vapour barrier.

Generally...
- put the higher spec insulation on the outside... putting fibreglass between the rafters, and high spec kinspan insulated plasterboard inside that will be a condensation risk.
- use a vapour barrier on the warm side of the insulation. In the case of insulated slabs, you would usually tack a vapour barrier (with plenty of lapping) on the rafter side of the slab.
- call or email the manufacturer (not the supplier or installer) of your chosen insulation, and ask them for a condensation risk analysis. They'll calculate it quickly and do it free of charge, and will advise on how to overcome any risk.
- sheepswool insulation can absorb quite a lot of moisture and still retain it's insulating characteristics. You will still need an analysis of the condensation risk though.


The condensation analysis will calculate the location of the dew point... you need it to be outside the vapour barrier.