New system struggling to reach room temp 21 deg

[Agile]

With a condensing boiler its much more economical with a lower flow temperature so the rad specs should now be quoted for a delta T 50°

In reality its possible to get more heat out by turning it up just at extreme cold times as long as you reduce it later. As it doesn't condense its about 12% less efficient.

Ideally your boiler should be used with a flow of no more than 70° and lower if you can get enough heat out.

The return should also ideally be 15-20° lower than the flow temperature.

Tony

 

[oldman2]

Thanks for that info Tony.

When I asked the installer where the knob should be set he just said leave it wound right up to 1 click from max

Now I know better....as long as the rads are man enough to deliver enough heat to the room of course

 

[chelseaboy2009]

if your boiler stat is set to maximum it doesnt matter: as long as your room thermostat and cylinder thermostat are set at the desired temperatues then they will cut out before the max boiler stat temperatue cut out at about 90 degrees C.

 

[oldman2]

Well its not looking promising, the installer has reworked his calcs and says the room is only a little low on rad size, he intends fitting a 1400x400 double panel double convector in place of the single and suggests that will be enough.
He says his calcs gave 4.956KW for the room.

Trying to confuse me now using KW when I was working in BTU's.

I cant very well argue with him as its his trade not mine, but I can see this not being the end of the story as its only 1.1KW more.

 

[gas4you]

1Kw = 3412 btu's

 

[oldman2]

Thanks Dave.

 

[Agile]

if your boiler stat is set to maximum it doesnt matter: as long as your room thermostat and cylinder thermostat are set at the desired temperatues then they will cut out before the max boiler stat temperatue cut out at about 90 degrees C.

The boiler stat controls the flow temperature!

Setting it to maximum will ensure the boiler does not operate efficiently in maximum condensing mode. The lower its set the more efficient!

Where did you do you efficiency qualification?

 

[stevebamford]

Hi Oldman

My view would be that if the rads are slightly too large you can turn them down a bit (or the TRV's will do that for you). I guess the system as a whole will take slightly longer to heat up but at least your living room would be nice and toasty

But if they are too small then you'll never be warm enough and you will never be happy with the system

Maybe you could ask him to go through the calcs in simple terms (and see if he made allowances for French Doors, fireplaces etc.) - That may reveal some issues ?

And I guess the worst case would be to pay a little extra and get the rads you want.

Good luck

Steve

 

[oldman2]

I agree Steve with all you say, I did try the "Ill pay for a bit of extra rad size" but he's i'm sure trying to take out a single and replace it with a double without draining down, hoping the pipework will mate up with the new rad.
I checked the pipework centers from the wall and the single there now is 67mm from the wall and the proposed double is 98mm from the wall so 21mm further out. This i'm fairly sure means a drain down or maybe freeze the pipes? to alter it.

View media item 9524 View media item 9525 View media item 9526
Thats how it is at present with the main gas supply running under the rad, the elbows rise to the feed to the rad from upstairs. Its already a pigs ear of pipe joints and couplers as they originally had a 5 or 600 deep rad there and the gas feed running on the carpet, I had them change that to raise up the gas from the floor meaning less room for the rad so they fitted a wider but only 400 tall one instead.

What I am finding now the systems been in and running for some months is a dirty trick with pipe clips, see how this pair has one off the wall.

View media item 9527
Every place there are 2 or 3 clips together only 1 has been drilled and screwed to the wall, the others have been slotted into each other to hold in place. What then happens is with the copper continually expanding and contracting the unfixed clips creap out of line from the others leaving the pipework hanging in free space.

Now im getting a bit peed off with this as I continually have to go round clipping the pipe clips back into the fixed one. Is this the way of modern plumbers? or do other usually fix all the clips?

 

[stem]

Ch should be able to raise a room to 21 degrees in an hour if the outside temp is minus one.

Is this correct? I've only ever seen the definition of Central heating quoted as "sufficient to maintain an internal temperature of 21 degrees Celsius when outside temperature is minus 1 degree Celsius"

To raise a room to 21 degrees in an hour when the outside temperature is minus 1 is a meaningless statement. Raise the room temperature from what, to 21 degrees in an hour? Assuming the outside temperature is minus 1, consider the following examples which would both need to be possible to fit namsag's definition.

1. The room could be 16 degrees before the heating comes on due to the previous days residual heat, so to get to 21, it only needs to increase the temperature by 5 degrees.

2. If the property has been unheated for a while, perhaps whilst the occupants have been away, the internal temperature could be 4 degrees, now the heating will have to increase the temperature by 17 degrees to reach 21. I doubt there are many, if any, domestic heating systems installed in the UK that could cope with that in one hour.

 

[oldman2]

Plumber has now agreed to fit a 400x2200 double convector double panel in place of the 400x1400 single panel.
I agreed to pay £40 towards the upgrade. He will now have to drain down to sort the altered pipework.

Nobody has had any comments on the slipping pipe clips, everyone guilty of doing the same

And what about Stem's questions re time to raise to temp?

 

[stevebamford]

Hey good news on the rad upgrade ! Worth the £40 I'd say

The clips sound well shoddy - You shouldn't need to reclipping things. How big is the installer company ? Was it the owner that fitted them - or one of his employees ? And have you mentioned it to them ?

Stems point sounds completely valid to me. (I'm a DIYer but maybe some of the Pro's could throw some light on it)

 

[JohnD]

OOI, have you got heavy lined curtains on that enormous glass wall? If not, you are spending a lot of money trying to heat the garden.

 

[Agile]

There is little available to act as authoritative information.

The general expactation is that when the property has been recently heated, say within 8-10 hours then it should reach the set temperature in one hour.

I would say that if the property has been unheated then it would take a "bit" longer.

With a condensing boiler, the set max flow would usually be 70°C but the user could turn that up to say 75°C if it had not been heated recently or if it was below -1C outside ( or windy as well which increases building losses. )

Tony

 

[oldman2]

Steve its a father and sons local small business Corgi number is in the 2000's range so has been going a while and was recommended.

The father just does the costings now and relies on the 2 sons to install, I think he needs to be a bit firmer with them.
I talked to Talon who make the clips and they say as I thought that every clip should be fixed and not rely on the dovtail jointing to hold it in place.

I will be asking them to change all the clips to doubles (center fix) or remove the pipes while drained down to drill the wall for proper fixing.

JohnD I do have fully lined heavy velvet full ceiling to floor curtains on that wall of glass