Older panel steel radiator outputs?

[bw65587]

Does anyone know how to calculate or where I can find the output (watts) for older panel steel radiators?

We have the following sizes in our 1970's house:

• 590mm (H) x 2080mm (W) Double (No fins)
  590mm (H) x 1760mm (W) Single (No fin)
  590mm (H) x 1600mm (W) Single (No fin)
  590mm (H) x 960mm (W) Double (No fins)
  440mm (H) x 1760mm (W) Double (No fins)

Additionally, we have some new radiators that have a logo on the end which could be a double D interlinked like 'DD'. Does anyone know what make they are?

Many thanks!

 

[D_Hailsham]

These are very approximate figures as manufacturers tables are not available. They are interpolated from existing data.

590mm (H) x 2080mm (W) Double (No fins) approx 2000W
590mm (H) x 1760mm (W) Single (No fin) approx 1100W
590mm (H) x 1600mm (W) Single (No fin) approx 980W
590mm (H) x 960mm (W) Double (No fins) approx 1000W
440mm (H) x 1760mm (W) Double (No fins) approx 1400W

 

[bw65587]

Very much appreciated!

May I ask a further question? How many watts should I then allow for our 162 litre cylinder?

Many thanks.

PS. Any idea who made the 'DD' rads?

 

[D_Hailsham]

How many watts should I then allow for our 162 litre cylinder?

Are you trying to size a new boiler? If so the normal allowance for a HW cylinder is 2kW. Using the existing rads as a guide is not always a good idea as the property may have changed - insulation, double glazing etc.

Don't be surprised if it gives an answer lower than your rad total. It does not mean you will have to replace the rads. It does mean you will be able to run the boiler at a lower temperature, thus saving fuel and reducing your bills.

If you want to size your boiler use either Sedbuk Boiler Calculator or EST online boiler calculator. The results will be the same, one is easier to use.

Any idea who made the 'DD' rads?

No.

 

[bw65587]

It's a long story! Basically, Glow-worm recommended an installer to us who proved himself to not know a lot about CH systems when he replaced our 36-year-old Glow-worm boiler with a new Glow-worm Ultracom 38hxi boiler. Worse was that we found out after the job was finished and Glow-worm disowned ever recommending him!

Anyway, we discovered that the Ultracom 38hxi boiler is massively over-sized for our house!

Before I made my original post, I had range rated the boiler down to 16kW. I just wasn't convinced it was correct being so low!

Using your estimated rad outputs, I have calculated I have a total rad output of 14kW before adding DHW, so 16kW in total.

Both of your suggested boiler-sizing sites say the same as you said they would, 12kW including DHW. It is a fully DG 1970's 4-bed detached house with cavity wall insulation and recently topped-up loft insulation.

So, I take it you're saying I can still down rate the boiler further to say 12kW and see how we get on?

 

[D_Hailsham]

Using your estimated rad outputs, I have calculated I have a total rad output of 14kW before adding DHW, so 16kW in total.

Both of your suggested boiler-sizing sites say the same as you said they would, 12kW including DHW.

So, I take it you're saying I can still down rate the boiler further to say 12kW and see how we get on?

Sorry to hear you had a cowboy installer. Fortunately you boiler can modulate down to 6.3kW

I suggest you try dropping the output to 12kW and monitor how well it copes with the cold weather. It's going to be a bit of an experiment to get it right.

The radiators are presumably pre-insulation, so are now oversized. One advantage of this is that they can run at lower temperatures, which means the boiler will condense more.

What controls do you have? If you do not have weather compensation it would be worth considering as you have oversized rads.

 

[bw65587]

I suggest you try dropping the output to 12kW and monitor how well it copes with the cold weather. It's going to be a bit of an experiment to get it right.

I dropped the output to 12kW last night and everything appeared to work fine. No issues this morning with either house or water being heated.

What controls do you have? If you do not have weather compensation it would be worth considering as you have oversized rads.

We have a programmable Glow-worm Climapro RF room stat but no weather compensation. Will have a look at that. Thanks for mentioning it.

Regarding the Climapro RF, we are also suffering from the boiler coming on at times outside of it's timed settings and it can't be the frost setting. I've lost count of the number of times I've had to go downstairs between midnight and 05:30 to turn it off. Are wireless stats prone to this type of thing? Should I consider replacing it with a wired one or could there be another cause?

 

[D_Hailsham]

I dropped the output to 12kW last night and everything appeared to work fine. No issues this morning with either house or water being heated.

Keep your eye on it, particularly when it gets colder. You may then need to turn it up a notch or two

We have a programmable Glow-worm Climapro RF room stat but no weather compensation. Will have a look at that. Thanks for mentioning it.

Good idea

Regarding the Climapro RF, we are also suffering from the boiler coming on at times outside of it's timed settings and it can't be the frost setting. Are wireless stats prone to this type of thing? Should I consider replacing it with a wired one or could there be another cause?

What is your ECO temperature setting? This is the one which should be used overnight. If it is too high and your house cold down quickly, the boiler will come on to maintain the ECO setting. I see that the manual recommends 15C. I think this is too high; 10C or lower would be more suitable. Mine is set to 5C but as the house temperature never drops more than 3 or degrees overnight it is effectively a frost setting or when the house is unoccupied for a long time.

I don't know about the Climapro, but RF stats are not prone to this problem. How far is the receiver from the boiler and other metal objects? How for is the controller from the receiver and how many walls between them?

Try temporarily moving the controller closer to the receiver (say overnight) to see if you still have the same problem.

 

[bw65587]

What is your ECO temperature setting? This is the one which should be used overnight. If it is too high and your house cold down quickly, the boiler will come on to maintain the ECO setting. I see that the manual recommends 15C. I think this is too high; 10C or lower would be more suitable. Mine is set to 5C but as the house temperature never drops more than 3 or degrees overnight it is effectively a frost setting or when the house is unoccupied for a long time.

It's set to the factory setting of 15C like you mentioned. Like you, I've never seen the room stat lower than about 18C but I understand what you're saying - the boiler may be coming on at a room stat reading of above 15C in order for it to not go below it. I hadn't thought of that! I thought the boiler would only kick in at 15C room temp.

I don't know about the Climapro, but RF stats are not prone to this problem. How far is the receiver from the boiler and other metal objects? How for is the controller from the receiver and how many walls between them?

Try temporarily moving the controller closer to the receiver (say overnight) to see if you still have the same problem.

There are 2 walls (in a straight line) between the stat and receiver. I don't know how radio waves travel but there is only 1 wall between the hall and kitchen where the 2 units are installed. The receiver is right beneath the boiler and the bottom edge of the receiver is at a height of 1.3M from the floor. I've just read the installation booklet left with us and it says it should be no less than 1.8M above the floor so that could be a cause. We do get some 'RF Err' messages now and again on the Climapro RF but the manual says that these are either 'no electrical supply' or 'EBUS connecting cable defective'.

As you suggest, I think I will leave the stat in the kitchen for a week say, to see if it happens whilst in the same room. I'll also consider getting someone in to resite the receiver 1.8M above the floor and further away from the boiler. They can also double check the wiring whilst at it. Who knows what the original cowboy's wiring could be like???

I'll keep you posted.

Many thanks for your attention. It has been very much appreciated!

 

[bw65587]

I've just done a quick experiment on the ECO setting.

Whilst outside of the timed period, I increased the ECO to 20.5C whilst the room stat said 21.5C. I then moved the room stat into the kitchen which is a cooler part of the house. The room stat slowly dropped to 19.5C before the boiler came on. There was plenty of time for it to come on whilst at 21.5C, 21.0C, 20.5C & 20.0C.

Anyway, not sure if above really proves anything as the drop in temp was forced over a shorter period than would be normally expected. That said, a quicker drop should have prompted the boiler to come on sooner!

Anyway, the stat's now in the kitchen and the ECO lowered to 10.0C. Let's see what happens!

 

[bw65587]

Anyway, the stat's now in the kitchen and the ECO lowered to 10.0C. Let's see what happens!

Whilst Climapro RF left in Kitchen next to receiver, boiler didn't wrongly come on outside of timed period in weeks so there was never a communication failure.

However, the moment Climapro RF moved back into Hallway, boiler would often come on at silly o'clock throughout the night.

Rewired receiver and placed above 1.8M from floor. It's been done for 5 days and on 3 nights, boiler has come on in the middle of the night so got BG out today. Their advice is that wireless stats are useless and prone to not working no matter what the make. Suggested replacing the Climapro RF with a wired Honeywell T6360B stat and using the in-built programmer in the boiler.

Any opinions on whether this is a good stat to replace it with or should I just get the wired version of the Climapro to replace it with although dearer option?

Many thanks for any advice!