New Boiler to replace a old Worcester 35CDi II

[j3oeff]

Best call baxi out as your having low kw rates out of your bath taps

Baxi rather than installer?

Best call baxi out as your having low kw rates out of your bath taps

 

[ShaunCorbs]

I would say so as I’m guessing your bath taps don’t have flow restrictiors in hence the correct flow rate and your only pulling on johns calculations 23kw

You can prove this by taking a gas meter reading then run the tap for 2 mins and take another reading and come back to us (aslong as it’s a metric meter eg not in ft/h

 

[John.g]

Measured Mains temp 7.5C

3.74 secs @ 31.2c 16.04LPM 26.52kw
3.86 secs @ 33.7c 15.54LPM 28.4kw
6.30 secs @ 36c 9.52LPM 18.92kw
10.16 secs @ 39.8c 5.91LPM 13.31kw
16.26 secs @ 41c 3.69LPM 8.62kw

Edit: Also corrected kw from post 31, mains are 7.5C, assumed originally at 9C.
4.13 secs @ 31.8c 14.52LPM, 23kw corrected to 7.5C mains = 24.62kw

 

[j3oeff]

I would say so as I’m guessing your bath taps don’t have flow restrictiors in hence the correct flow rate and your only pulling on johns calculations 23kw

You can prove this by taking a gas meter reading then run the tap for 2 mins and take another reading and come back to us (aslong as it’s a metric meter eg not in ft/h

Before and after

 

[ShaunCorbs]

Sorry they don’t update fast enough needs to be the gas meter

 

[Scott_D]

Could also be a mixer shower passing or diverter issue.
I would call the installer after the holidays.
You have some hot water and heating so not an emergency but needs looking at ASAP

 

[j3oeff]

Sorry they don’t update fast enough needs to be the gas meter

Gas meter doesn't show anything from the outside which I found odd. It was just blank which is why I resorted to smart meter

 

[ShaunCorbs]

Press any button ? Should light up

 

[j3oeff]

Could also be a mixer shower passing or diverter issue.
I would call the installer after the holidays.
You have some hot water and heating so not an emergency but needs looking at ASAP

Would a dodgy shower tap cause such issues? I noticed when my old boiler was in, the ensuite shower has one tap which turns left and right for 25 upto 50c with a little red button which needs to be pushed to go out 38c. This had been playing up and was red hot on any temp unless I turned it right down to 25c then it went cold. There was no in between.

I've just had a shower tonight and whilst it was on 38c it was nice but not overly hot but turning it up to 45/50c didn't really increase the temp much? Or is that nothing to do with my issues.

 

[j3oeff]

Press any button ? Should light up

Before 2 minutes hot tap run 380.264 and after 380.304

 

[ShaunCorbs]

And this was with the bath tap running just checking ?

 

[John.g]

If that's m3i in 2 mins then 0.04 in 2 mins = 1.2m3/hr approx 13kw or about 11kw at 85% efficiency. Bath tap 0n??

 

[ShaunCorbs]

11.59net (12.86gross)

 

[j3oeff]

And this was with the bath tap running just checking ?

No, kitchen one. Should it of been the bath tap? If so I'll do it in the morning now

 

[j3oeff]

If that's m3i in 2 mins then 0.04 in 2 mins = 1.2m3/hr approx 13kw or about 11kw at 85% efficiency. Bath tap 0n??

Kitchen tap on full.

 

[ShaunCorbs]

No, kitchen one. Should it of been the bath tap? If so I'll do it in the morning now

Yes please

 

[j3oeff]

Will in the morning. Thanks for helping with this chaps. Appreciate it and learning at the same time.

 

[John.g]

If these two (post31) then
12.09 secs @ 42.4c 4.96LPM, 12.07kw
18.10 secs @ 54.4c 3.31LPM, 10.83kw
Average 11.45kw

Very close to flow/temp calc??falls off with increasing temp

Might be something to do with combi temp control? as output decreases with increasing HW temp and boiler gets close to rated output at reducing temps.

 

[John.g]

Had a look at the Baxi830 manual, it states minimum flowrate 2 LPM but recommend 2.5 LPM and the minimum output is 6.1kw.
The lowest test flow reading was 2.74LPM (bathroom tap) which gave a measured temp of 41.1C from mains at 7.5C = 6.42kw.
With the DHW temp control to max, 60C, and if the measured HW temp was 60C, then 10.04kw required so no reason why the boiler shouldn't have achieved this.

 

[j3oeff]

Some more 2 minute hot tap runs with readings.

Bath start 383,730 finish 383,812
Main bathroom sink tap start 383,812 finish 383,894
Ensuite sink tap start 383,894 finish 383,973
Ensuite shower set at 38c start 383,973 finish 384,028