Do I have enough radiators

[tommyleestaples]

Hi all,

 

I am just in the process of selecting radiators for a quite large kitchen, diner and open plan playroom. The room is 7x7m with a wall in-between but the area is still open as you can see on the plan. We have bifolds measuring 3.6m x 2.19m with double glazing and a double glazed window 1.09m x 1.12m. 

 

The suspended timber floor underneath is insulated with 100mm PIR and the rooms above are heated. 

 

Would the number of radiators shown on my plan be enough to adequately heat the space?

 

I would really appreciate your comments as we are not having underfloor heating.

 

 

[JohnMo]

First do a room heat loss. That will tell you. 

 

You make no mention of heat source or flow temp, these all have an impact on suitability.

 

BTU, thought people stopped using them 40 years ago unless your from the USA.

[marshian]

2 hours ago, JohnMo said:

BTU, thought people stopped using them 40 years ago unless your from the USA.

 

Up to about 2 years ago that's all I used....................

 

Mainly because I had a dos based programme for calculating rad sizing for rooms and that's the only unit of measure it used

[SteamyTea]

Isn't power BTU/hour.

Conversion factor 1 BTU = 0.29 W

[RobLe]

I think BTU is just used for heat energy, and it does have one advantage - its a quantity not a rate as kW is.  So BTU avoids the ‘rate trap’ that kW gets people into, persuading them to use kW/h.  Having said that, a bit of Googling shows btu and btu/h being used interchangeably, oh well.

So those rads at 50C could produce 4.6kW if on at 50C, which would heat two of our home on a cold day.  As others have indicated, there’s still more to it: what’s the U value of all the walls, floor(ok 100mm celotex), glazing, and what is the heat source hence temp (gas/heatpump) ?  If it’s all new spec and gas heated, then almost certainly yes.  But we would all aspire to a heatpump one day…

 

[tommyleestaples]

The external walls are cavity walls full filled with Knauf DriTherm 32 150mm Cavity Wall insulation so when using a calculator gives a u value of 0.19 W/m2K. Floor is 100mm Celotex, double glazing and it is a gas combi boiler.  The boiler will be running at a flow temp of 60C

[SimonD]

16 hours ago, JohnMo said:

BTU, thought people stopped using them 40 years ago unless your from the USA.

 

You would have thought since we moved over to metric over 40 years ago but go onto sites like screwfix and they're all listed in BTU. One of my suppliers and radiator manufacturer recently republished their catalogue in BTU changing it from kW - I phoned the manufacturer up to ask what was going on and they replied as if I had gone mad! So I asked them what unit is used to complete heat loss calcs and they still were blank.

 

It's just bonkers....

[JohnMo]

29 minutes ago, SimonD said:

 

You would have thought since we moved over to metric over 40 years ago but go onto sites like screwfix and they're all listed in BTU. One of my suppliers and radiator manufacturer recently republished their catalogue in BTU changing it from kW - I phoned the manufacturer up to ask what was going on and they replied as if I had gone mad! So I asked them what unit is used to complete heat loss calcs and they still were blank.

 

It's just bonkers....

Watch any quiz show and 20 to 40 years old contestants have zero clue the difference between centimetres and millimeters. That is all they should learn at school. I'm in my 60's and have only used metric most my life, using imperial on really old stuff only.

[marshian]

27 minutes ago, JohnMo said:

Watch any quiz show and 20 to 40 years old contestants have zero clue the difference between centimetres and millimeters. That is all they should learn at school. I'm in my 60's and have only used metric most my life, using imperial on really old stuff only.

 

Same age but I cross over between metric and imperial depending on factors

 

Really small stuff - Thou (I have a automotive habit so spark plug gaps and tappet clearances)

 

Small stuff - CM and MM and to a push M

 

Bigger stuff - Inches and Feet (Boats are still x footers and I'm 5 foot 13 inches 😉 )

 

Really big stuff - Miles (although knots and fathoms if I am boating)

 

I don't do lbs and ounces - I do Kgs but weight in stone is much easier for me to translate in my head

 

Still work out miles per gallon (the proper sized one not the poxy little one the USA use) even thou I buy fuel in litres

 

It's all a little weird really!!!

[marshian]

Anyway back to topic - what's the reason for using T11's @tommyleestaples 

 

Space constraint?

 

Already fitted?

 

Asthetics?

[tommyleestaples]

Hi I am using T21

[marshian]

36 minutes ago, tommyleestaples said:

Hi I am using T21

Sorry fat fingers - same questions still apply

[tommyleestaples]

This is all new to me so all the websites that sell radiators have a BTU calculator. 
 

I have run the calculator for all rooms to calculate the BTU I need. I have chosen radiators that exceed the BTU given as I could turn down the radiators if needed.

 

I was initially going to get Type 22 radiators but couple of reasons. I seem to have type 21 in all the rooms on the original part of the house. Also I have tried to go for radiators that look in proportion to the wall they are on. With type 22 I would need a much smaller radiator and the BTU output still massively exceeds what the calculator states I need for each room so type 21 sort of fitted the bill. Could get radiator for right size for the wall and it still exceeded the BTU I needed by 10-20%.

 

however I have not ordered them yet so I am open to suggestions if I have got this all completely wrong

[marshian]

16 minutes ago, tommyleestaples said:

This is all new to me so all the websites that sell radiators have a BTU calculator. 
 

I have run the calculator for all rooms to calculate the BTU I need. I have chosen radiators that exceed the BTU given as I could turn down the radiators if needed.

 

I was initially going to get Type 22 radiators but couple of reasons. I seem to have type 21 in all the rooms on the original part of the house. Also I have tried to go for radiators that look in proportion to the wall they are on. With type 22 I would need a much smaller radiator and the BTU output still massively exceeds what the calculator states I need for each room so type 21 sort of fitted the bill. Could get radiator for right size for the wall and it still exceeded the BTU I needed by 10-20%.

 

however I have not ordered them yet so I am open to suggestions if I have got this all completely wrong

 

It's a different approach if you are using online calculators based on room volume then please be aware they will probably oversize the requirement.

 

As others have said you really need to do a whole house heat loss - but if you are already running 60 deg flow for the rest of the house then I guess you need to size the rads for the new area with the same temp regime and just do a heat loss of that area.

 

With your current rad positions you should get a good even spread of heat and as you say you can turn the rads down if they are a little over size whereas if you undersize a rad you can't really turn it up (all you can do is up the flow temp) or replace it for a larger one

 

 

[tommyleestaples]

Would you recommend going for type 22 radiators then on the basis can turn them down and they are heating a big open space

[marshian]

25 minutes ago, tommyleestaples said:

Would you recommend going for type 22 radiators then on the basis can turn them down and they are heating a big open space

I’d be doing something very different - I’d be sizing my rads for the lowest flow temp my boiler can run at but I’d be looking to do that for the whole house in order to get the boiler efficiency to high 90 % efficiency (ie 97-98%) that would make me heat pump ready for when the boiler needs replacement with just the addition of a HW tank (cos you currently have a combi so no HW tank) 

 

However I appreciate that everyone has a budget and sizing for 60 deg might be what your budget accommodates.

 

I wouldn’t mix and match and have part of the house with oversized rads and the rest of the house sized for 60 deg C flows. 

[Nickfromwales]

That 1800x420 on the long left wall....why is that a vertical? That should be a double rad, same height as the 600x700 and then the '1800x420' rad should be sent much further down that long wall, eg towards the bi folds. That arrangement will create a cold 'end' to that room as the vertical rad to the right of the bi folds will do next to nothing unless it's roasting hot. You show T50 which is not much use to a vertical / decorative radiant panel like that (which doesn't convect well at all).

41 minutes ago, tommyleestaples said:

Would you recommend going for type 22 radiators then on the basis can turn them down and they are heating a big open space

If you aren't having 2x vertical down there, and the one one the long left wall can be a big type 21, then you'll be fine if the other 2 600x700 are both type 22's.

Type 21's do look far less intrusive in open areas, but you still need more heat in that space imho (I've been installing CH for 30+ years btw). If the type 22's don't fit the spaces they are in, then simply make them longer type 21's.

Much better to be turning a big rad down, as you cannot turn a small one up , plus if you then end up running much higher flow temps the boiler efficiency will drop off at a steep rate.

[tommyleestaples]

Sorry Nick I should have added the other kitchen units on the drawing, not sure why I missed them out.  The reason for the vertical radiators is because of the limited wall space. on the long left wall there is kitchen units and then a boxed in soil pipe so a decent size vertical radiator fits in the space. 

[Nickfromwales]

Ah, ok lol. Thanks. ☺️ 

 

I’d definitely be beefing up the two standard radiators then, looking at location they could become type 22’s without impact?
 

Vertical rads don’t do a great amount, and please realise my focus for the end result is always on the adverse weather days, not just ‘everyday’ .

 

I won’t install a system where the client turns the room stat up to 22°C and the system cannot get there / struggles to get there, because it’s blowing a hoolie outside and it’s -3°, and you should be looking for lower flow temps. 
 

One get out of jail card is to turn the violet flow temp up during the worst of the winter months, but then efficiency will suffer when you need it most. 

[Alan Ambrose]

>>> Anyway back to topic

 

There was a topic? I thought these threads were all free association, no? Oh I see…