Weird heat levels from different taps

muggles said:
24kW is the lowest power combi you can buy, so it shouldn't be too surprising that it's struggling to keep up with high flow rate fittings. As with your bath, does the shower temperature also improve if you reduce the flow rate?
Click to expand...

We have no high flow rate fittings
 
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And maybe a *slight* Improvement in the shower, but nothing to write home about.

My confusion lies in the two outlets producing scolding water and the other two lukewarm - even though they are the same flowrate.
 
peterb20 said:
We have no high flow rate fittings
Click to expand...
Higher flow rate then, if you want to be awkward. The point still stands - your bath and shower are outstripping what your boiler is capable of delivering, resulting in cooler water than you'd like. Reduce the flow rate through them and all will be well
 
peterb20 said:
My confusion lies in the two outlets producing scolding water and the other two lukewarm - even though they are the same flowrate.
Click to expand...
Have you actually measured the flow rates and temperatures produced at each outlet, or are you just guessing by eye and feel?
 
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muggles said:
Have you actually measured the flow rates and temperatures produced at each outlet, or are you just guessing by eye and feel?
Click to expand...
Agree, everyone should have a big bowl and stop watch for a basic relative measurement. Temperature more tricky, even a digital meat thermometer or an IR thermometer would get an accurate enough temperature if you have one.
Op, Also measure the temperature of the cold tap after running it for a minute.
 
Ok right so, I dialed the rising main down to a less powerful flow as an experiment, so these figures are based on the reduced flow due to that:

Kitchen 6.5l/m flow rate, 13deg cold, 54deg hot
Bath 7.3l/m flow rate, 43deg hot.

I see the higher flow rate means it will be colder, but both flow rates are well within the 12.4 flow rate the boiler is rated at.

With the bath at 43deg, it would need a bit of cold added, but at that flow rate would also take hrs to fill!

Oh and the boiler is 30kw for dhw, rather than the 24kw I stated earlier.
 
John D v2.0 said:
Yes 7.3l at 30c rise doesn't sound good. For 30kw I'd have to work it out and that's the heat input, but you should get more than that.
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So are you saying their is a possible boiler issue too? Still doesn't explain the difference at different outlets though!
 
Your boiler should be producing a 35°C rise (between incoming main & temp at a tap) @ 12.4 l/min so the performance you're reporting doesn't seem right.


peterb20 said:
Still doesn't explain the difference at different outlets though!
Click to expand...
Yes it does - higher flowrate = lower temperature rise.
 
peterb20 said:
So are you saying their is a possible boiler issue too? Still doesn't explain the difference at different outlets though!
Click to expand...
Yes sounds like a boiler issue or a gas supply issue.
Energy transfer is measured in kW or alternatively degrees per litre per second. Increase the litres per second and the degrees decreases. If you multiply them together you should get a similar figure.
7.3x30 = 6.5x41 in theory
However it seems your boiler has an issue so it may be getting incorrect readings from one of the temperature sensors.
Try putting both the taps on full blast and then gas rate the boiler using the gas meter.
Ie take a reading of the smallest digit or spinning dial, wait a minute and take it again, then input into one of the online calculators.
 
Newboy said:
Do you have the benchmark from the boiler installation?
Click to expand...

I do, it states 18deg in, 58deg out @ 18l/min

So this is how pointing towards the boiler not working quite as it should be to have such a drop in output, correct?
 
peterb20 said:
So this is how pointing towards the boiler not working quite as it should be
Click to expand...
Yes or lack of gas,see below
John D v2.0 said:
it seems your boiler has an issue so it may be getting incorrect readings from one of the temperature sensors.
Try putting both the taps on full blast and then gas rate the boiler using the gas meter.
Ie take a reading of the smallest digit or spinning dial, wait a minute and take it again, then input into one of the online calculators.
Click to expand...
 
John D v2.0 said:
Yes or lack of gas,see below
Click to expand...
I will get the installer in then and get it serviced. We've had a new meter installed recently and the guy who did that didn't go out to the boiler so maybe the gas flow has been changed during Ng that to affect it. I'm in over my head now but appreciate everyone's help in pointing the finger towards the boiler being the problem
 
Interesting, it may be that the new meter has an issue or has caused an issue. Definitely a good idea to call someone in, they can check the working pressure at the meter (and at the boiler) very quickly and easily and narrow down the problem if any with the supply
 
D

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