hot water temperature fluctuation

[humey53]

Why is it that when I turn on my hot water taps at home

1. the time taken for the water to run hot varies

2. Often it can run hot then run cold before staying hot.

I have a Worcester Bosch combi boiler (can't remember model and I'm at work now anyway), installed about five years ago, serviced annually by British Gas

I have looked for this question before posting; if I've missed it I apologise.

 

[WabbitPoo]

That's how combis work. The burst of hot is because there's water sitting within the the hot bit of the boiler, the cold burst is that which replaced it, then the boiler gets the chance to really kick in and you get hot again. Get used to it.

As to why the initial period varies, it depends on the water in the pipes at the time (eg has someone else just run a hot tap somewhere).

Don't hsit a brick over it - its how they work.

 

[humey53]

OK, understand that.

Is there a method to reduce the amount of cold water, as sometimes it seems to go on for ages?

 

[joe-90]

It all depends on your pipe run. The more pipe - the more cold. Sometimes dodgy installers will also leave the bath feed at 22mm when converting to a combi - so you have lots of cold water locked into a big pipe.

 

[humey53]

It all depends on your pipe run. The more pipe - the more cold. Sometimes dodgy installers will also leave the bath feed at 22mm when converting to a combi - so you have lots of cold water locked into a big pipe.

Ain't got that problem, but thanks for the tip.

Looks like the answer is patience.

 

[WabbitPoo]

yep. all the "saving" of a clever new boiler, gone down the drain via your water meter.

 

[Agile]

You could test the start up delay of your boiler by holding the hot outlet pipe UNDER the boiler and getting someone else to turn on a hot tap.

Different boilers have different hot water start delats. The Ideal Response was one of the worst with about 15 sec before it starts to warm up. Oddly the 20 y.o. Ideal Sprint and the G-W Swiftflow were sone of the fastest!

Tony

 

[humey53]

You could test the start up delay of your boiler by holding the hot outlet pipe UNDER the boiler and getting someone else to turn on a hot tap.

Different boilers have different hot water start delats. The Ideal Response was one of the worst with about 15 sec before it starts to warm up. Oddly the 20 y.o. Ideal Sprint and the G-W Swiftflow were sone of the fastest!

Tony

if 15 seconds is the worst, what's resonable to expect on my Worcester Bosch? Might be academic if the delay time can't be reduced?

 

[WabbitPoo]

I never timed it, but my old Ideal Icos Isar pile of carp boiler took ages, and my nice shiny Worcester Greenstar Bosch thing is a lot quicker.