Real world vs theoretical hot water temperatures

[jakeycrx85]

Have you carried out a gas rate?
I wonder if the weir cup you are using is worn.

As I've already said about 10 times I don't touch anything to do with gas

 

[roguetrader]

So we are 1 degree out, which may or may not be down to your measuring instrument.
Let me get my slide rule and scientific calculator out and try and see where it's all gone wrong.

You're really don't get it done you. Most instruments tend to go out on their zero but maintain their linear scaling.

For example my thermocouple could have a zero error of -1. It would read -1 degrees at 0 degrees and 99 degrees at 100 degrees.

It could also have a zero error of +1. You just end up with an offset. Both of these thermocouples would still measure the temperature rise just fine because I am only interested in the difference between my incoming water and my DHW. The actual temp readings are irrelevant.

Oh but I do get it, I really do.
What I don't get is the reason you're making such a fuss over the results of your totally irrelevant experiment.
The reason no one else has done it is it proves absolutely nothing.
You'd be better off treating yourself to a years subscription to razzle and some kleenex.

 

[Steelmasons]

You seem to be an authority on the subject which is why I am asking for advise...
So a gas rate requires a RGI?

 

[TCCHeating]

No you haven't. What results have you seen on a 24kw boiler? Or any boiler

Eh?

As I said before. Every time I go to diagnose a combi boiler where customer says hot water is not as hot as usual. I do a gas rate. Check flow rate and check temperature differential. Basic tests to diagnose the problem

I don't have a record of the results but last one I repaired it was nothing to do with the boiler. Turned out to be a passing shower valve.

 

[AGAS]

As I've already said about 10 times I don't touch anything to do with gas

don't be frightened about touching gas , you don't need to to do a gas rate glad to see your learning

 

[jakeycrx85]

So we are 1 degree out, which may or may not be down to your measuring instrument.
Let me get my slide rule and scientific calculator out and try and see where it's all gone wrong.

You're really don't get it done you. Most instruments tend to go out on their zero but maintain their linear scaling.

For example my thermocouple could have a zero error of -1. It would read -1 degrees at 0 degrees and 99 degrees at 100 degrees.

It could also have a zero error of +1. You just end up with an offset. Both of these thermocouples would still measure the temperature rise just fine because I am only interested in the difference between my incoming water and my DHW. The actual temp readings are irrelevant.

Oh but I do get it, I really do.
What I don't get is the reason you're making such a fuss over the results of your totally irrelevant experiment.
The reason no one else has done it is it proves absolutely nothing.
You'd be better off treating yourself to a years subscription to razzle and some kleenex.

Why is it irrelevant? It's got to be a good indicator of boiler performance which is what this forum is all about isn't it?

You seem to be an authority on the subject which is why I am asking for advise...
So a gas rate requires a RGI?

I don't proclaim to be an expert on gas. I'm just asking a simple question about flow and DHW temp which nobody seems to be able to answer.

Eh?

As I said before. Every time I go to diagnose a combi boiler where customer says hot water is not as hot as usual. I do a gas rate. Check flow rate and check temperature differential. Basic tests to diagnose the problem

I don't have a record of the results but last one I repaired it was nothing to do with the boiler. Turned out to be a passing shower valve.

Do they normally achieve the specified rise when in good working order?

What do you do if the flow rate isn't at that what is specified in the manual? Mine is rated @ 35 degrees 9.4 l/min but I only get 8 l/min.

 

[TCCHeating]

Do they normally the specified rise when in good working order?

do you do if the flow rate isn't at that what is specified in the manual? Mine is rated @ 35 degrees 9.4 l/min but I only get 8 l/min

Some boiler manufacturers quote flow rate at 35 degree rise because it is industry standard. But they actually fit a flow restrictor to give you a 40 degree rise

 

[jakeycrx85]

Do they normally the specified rise when in good working order?

do you do if the flow rate isn't at that what is specified in the manual? Mine is rated @ 35 degrees 9.4 l/min but I only get 8 l/min

Some boiler manufacturers quote flow rate at 35 degree rise because it is industry standard. But they actually fit a flow restrictor to give you a 40 degree rise

Do they achieve their stated rise though? When new or in good order?

 

[AGAS]

if you got 35 degree temp rise what are you worried about , but SOME manu's play around with temp rise figure but results are the same really ( most times ) .

 

[jakeycrx85]

I'm just interested to see what happens in the real world but it appears nobody knows the answer. I just assumed you guys would do this kind of thing to check out how a boiler is functioning.

 

[AGAS]

As I said before. Every time I go to diagnose a combi boiler where customer says hot water is not as hot as usual. I do a gas rate. Check flow rate and check temperature differential. Basic tests to diagnose the problem

I don't have a record of the results but last one I repaired it was nothing to do with the boiler. Turned out to be a passing shower valve.

 

[TCCHeating]

Do they achieve their stated rise though? When new or in good order?

Yes

I just assumed you guys would do this kind of thing to check out how a boiler is functioning.

We do

 

[jakeycrx85]

As I said before. Every time I go to diagnose a combi boiler where customer says hot water is not as hot as usual. I do a gas rate. Check flow rate and check temperature differential. Basic tests to diagnose the problem

I don't have a record of the results but last one I repaired it was nothing to do with the boiler. Turned out to be a passing shower valve.

What do you do if the flow rate isn't what is specified in the boiler manual?

 

[jakeycrx85]

If my boiler was achieving a 35 degree rise but only at 6 l/min then there would definitely be something wrong with it.

 

[AGAS]

I've got a funny feeling your boiler is not performing well, why don't you just tell us what your problem actually is then we might be able to help .