House very difficult to heat...

[Aragorn84]

So i've been putting up with this for a while, but i'm wondering if theres anything i'm overlooking or doing wrong.

We have a 1920's semi, brick built cavity walls over two floors. 1st generation double glazing all round, thats getting on a bit. 300mm rockwool loft insulation, no cavity wall insulation. 20kw system boiler feeding radiators in each room.

In the cold weather (ie now) i find the house is almost impossible to keep warm. I work from home, but i avoid running the heating all day as it just seems to chew through gas and not really make much of a dent in the temperature. I tend to sit in the front room at my desk, with the door closed, and 1kw of fan heater topping up the warmth during the day. This gets the room up to a comfortable 20-21c and holds it there with a ~50% duty cycle. The rest of the house ofcourse is freezing.

When the boiler comes on around 5pm, the house just doesnt seem to get warm. There is three radiators downstair, one in the front room, one in the back room/lounge and one in the hall. Lounge is set to 5 on its TRV (room stat is in here), hallway and front room set to 3. Tonight for instance the lounge temperature was at 14c at 5pm. heatings been on for an hour, and its climbed to 15.5c, and thats with the lounge door shut, if i left the door open it wouldnt have climbed at all. If the door remains shut, it'll very slowly climb and might get to 21c by the time the boiler shuts off at 10pm. The hallway and kitchen (connected together essentially) is permanently freezing, cranking the hall radiator up seems to have little to no effect. This also means that any time you move between the rooms or goto the kitchen, any heat you've managed to build up seems to woosh away and get replaced with a cold chill from the hallway.

In the really cold weather a few weeks back, i ended up running my fan heater in the lounge more or less all evening, as the radiator was struggling to get the temp much over about 17c.

Last week i measured the flow and return pipes at the lounge radiator, and got 55c in, 40c out. I tweaked the lockshield to get it to a drop of 9c. 55c in seems a bit low, given the boiler stat is set as high as it will go. No real effect to the room temperatures. Radiators all feel hot to the touch.

I did an experiment a few weeks ago, running the boiler all day. In the time its usually off (9-5) it managed to chew through 2 units (cubic-ft) of gas and yet the rooms were still lukewarm and the hallway still freezing.

Its really getting on my nerves now, i should be able to put my heating on, and have the house heat up to a comfortable temperature, without literally sitting shivering. I wouldnt mind so much if it ripped thru the gas doing so, but chewing up gas and feeling no benefit from it is really frustrating.

Any thoughts?

I've a sneaking suspicion that the radiators are essentially too small, but that doesnt explain how the system is managing to rip thru so much gas. The heat has to be going somewhere?

 

[JayPage]

Having cavity wall insulation should make quite a bit of difference. You can also do some calcs to check you have the right size radiators. Are the radiators hot from top to bottom? Is the boiler new or old? Are there draughty? There's so many factors that. An effect the efficiency of your heating system.

 

[Aragorn84]

The radiators are all hot evenly, they are however all singles.

front room radiator is 2000x600 (curved around the bay window) and room is about 3m square
lounge radiator is 1100x600 and room is about 3mx4m
hall radiator is 1400x700 and the hallway and kitchen combined are about 7mx2m

No idea why the kitchen doesnt have its own radiator, i guess its just too small to easily fit one in.

Boilers about 10 years old, non-condensing system boiler.

Hot water is on a copper cylinder in the bathroom, gravity fed from the boiler (not pumped)

The house does seem pretty draughty, especially when its windy the house it markedly colder. From what i can tell, the draughts seem to come from the windows, however as a test i tried replacing the rubber sealing strips on the kitchen window, and it made no difference at all to the amount of air seeping through. From what i could see, the frame simply didnt seem to pull movable part in hard enough against the fixed bit to effect a good seal.

 

[JayPage]

A good start would be cavity insulation. This can be done for virtually no cost to the customer. A majority of a radiators heat comes from convection rather than radiation so maybe also look at upgrading them if they are under performing.
It may also be a thought to have the house energy checked, this could locate heat loss areas via a thermal image device. What was the flow temp directly out of the boiler before it serves any radiators?

 

[DP]

If boiler is working flat out, then heat is going someplace else.

Older boilers running flat out would have an output of about 85 degree C. Cast iron boiler would have a drop of 11 degrees at the input to the boiler. What you need to look for is, where does this heat disappear. In a nutshell, water leaves the boiler at 85, it goes to the first radiator and will still be at 85. By th time his flow reaches the furthest rad, it might have dropped to 80

The closest rad should be restricted such that a deluge does not flow through it, but the flow be controlled to show a difference of 11 degrees. If the rads close to the pump use up most of the pump power, flow to final rads will be slow and input temperature to these will be poor

Another area that creates havock, is the cylinder if is pumped flow. Check the temperature across the indirect coil- it too should show 11 degree difference with heating on

If plumbing is incorrectly sized you can have issues. Pump speed also should be looked at. Creating zones will reduce you fuel expenditure.

You problems are basic- any respectful heating person should be able to resolve the issues

 

[rpevans]

You say that you only have 55c at the flow connection to your lounge radiator. There lies your problem This should be more like 70 or 80c. What is the temperature of the flow pipe from the boiler? Can you turn it up?
You also have a TRV in the same room as the room stat. Turn this to max or take it off completely.
Hope this helps.
Rich

 

[Agile]

Have you had your boler properly serviced and checked?

As stated you need a flow temp of 80 C to get the house up to temp.

Its cheaper to heat just one room with electric than the whole house.

Turn off rads in unused rooms!

Get cavity insul as this saves 25% on gas bill and makes the house so much warmer!

Tony

 

[RigidRaider]

300mm in the attic isn't enough, you ought to double that.

 

[JayPage]

300mm in the attic isn't enough, you ought to double that.

2 foot of insulation? Seems alot to me. I've got an a rated house and I'm sure mines 300mm odd

 

[dcawkwell]

Sort the boiler and plumbing out.

The boiler should be giving you at least 70 degrees to the radiators.

Once that is sorted you need thick curtains.
Ensure the curtains do not cover the radiators.

Remove any drafts from windows and the like.

If room not getting warm you need more modern radiators with
double convectors.

Had the same problem in my house. Radiator would only get it to 14 or 15 degrees in cold weather. New modern radiator 20 degrees.

 

[Aragorn84]

I'll check the flow temp when i get a chance, probably means the weekend as i'll need to pull the washing machine out to get at it, as the pipes are boxed in above the worktop. Control on the boiler is set to maximum (6). The lounge rad is the first one in the system, so i'd expect it should be the hottest.

I've been hunting down draughts, the kitchen windows pretty bad, so i'm going to try adding some foam sealing strip round the frame to see if that helps it actually seal when closed.

The loft hatch was also broken leaving a ~50mm wide strip along one end, so i've cut a new board for that and installed it.

The other big issue i've realised is the bathroom, theres no extractor, so we leave the window open when we've been in the shower (ie every morning) and keep the bathroom door shut to let the condensation/steam ventilate away. Often this gets forgotten about though and so it remains open all day, obviously gobbling up lots of heat, especially given the non-TRV radiator is also in there. Will need to start closing that an hour or so after using the shower, and investigate getting an extractor fan installed.

One wall of the lounge is essentially all glass, as it has a full height patio door/window thing, so i suspect some thick curtains over this will help too.

Obviously now we're through the worst of the weather, so its likely i wont find out if any changes i've made are successful until next winter, though i guess we might get another cold snap yet.

Cheers

 

[dcawkwell]

I'll check the flow temp when i get a chance, probably means the weekend as i'll need to pull the washing machine out to get at it, as the pipes are boxed in above the worktop. Control on the boiler is set to maximum (6). The lounge rad is the first one in the system, so i'd expect it should be the hottest.

I've been hunting down draughts, the kitchen windows pretty bad, so i'm going to try adding some foam sealing strip round the frame to see if that helps it actually seal when closed.

The loft hatch was also broken leaving a ~50mm wide strip along one end, so i've cut a new board for that and installed it.

The other big issue i've realised is the bathroom, theres no extractor, so we leave the window open when we've been in the shower (ie every morning) and keep the bathroom door shut to let the condensation/steam ventilate away. Often this gets forgotten about though and so it remains open all day, obviously gobbling up lots of heat, especially given the non-TRV radiator is also in there. Will need to start closing that an hour or so after using the shower, and investigate getting an extractor fan installed.

One wall of the lounge is essentially all glass, as it has a full height patio door/window thing, so i suspect some thick curtains over this will help too.

Obviously now we're through the worst of the weather, so its likely i wont find out if any changes i've made are successful until next winter, though i guess we might get another cold snap yet.

Cheers

You just need to feel or measure the flow pipe into the radiator or the radiators temperature. It should be 70 degrees.

 

[Aragorn84]

yeh, the pipe into the rad was measuring 55c, i wanted to check the pipes straight out of the boiler though as a comparison.

I'm also going to get a better thermometer, as i was using a kinda crappy plastic thing.

 

[TheGasMan26]

Sounds like you definitely have a problem if your boilers set to max, what boiler do you have?

From the sound of your rads they are designed to be running at a flow of 70-80c as mentioned, but until you find why your boiler isnt kicking this out your gonna be cold.