Cold water pressure drop after new combi install

[davemuk]

Hi ukplumbers.

Last week I had a new combi (worcester bosch 28i junior) installed which replaced my old hot water tank system. Everything went well except I've noticed about a 20% drop in cold water pressure to all taps/shower in the house (the main stop tap has been checked to see if it's fully open). Is this a normal side effect of a combi install ?

The cold water pressure is still very useable but when the electric shower is on and someone flushes the loo, the effect is a little more noticeable now.

Any ideas as to the cause ?

Dave

 

[mickie]

hot water yes, not cold

 

[diamondgas]

If they came in a tank they could have squished the old lead feed outside!! LOL

Ask your installer back ... Possibility that there's an issue with the main isolation valve if all taps are affected!

 

[mickie]

turn all your taps off, then turn on one tap, if it comes out fast initially then slows back down, you have the pressure there, just not the flow rate, so as diamondgas has said, they've probably turned off the main stop tap and the washer has probably come off inside, slowing down the flow of water

 

[davemuk]

Thanks for the quick replies - I will try the taps suggestion.

 

[tackleburger]

Your toilet was probably tank fed before so wasn't a noticible as the tank would fill pretty slowly with just one flush. Now you are 100% mains you will notice these things especially on the hot. Perhaps your pressure or flow isn't ideal for a combi. This should have been checked before the job took place. You need about 20l per minute idealy with a pressure of no less than 1.5 bar. Although less than this works you do start suffering these symptoms the lower it gets. It doesn't sound that bad to me but you know best.

 

[davemuk]

Your toilet was probably tank fed before so wasn't a noticible as the tank would fill pretty slowly with just one flush. Now you are 100% mains you will notice these things especially on the hot. Perhaps your pressure or flow isn't ideal for a combi. This should have been checked before the job took place. You need about 20l per minute idealy with a pressure of no less than 1.5 bar. Although less than this works you do start suffering these symptoms the lower it gets. It doesn't sound that bad to me but you know best.

Both toilets in the house are mains fed.

It's not a do or die situation, I just wanted a reason as to why the pressure has dropped a little. I don't like unexplained changes

Also, all the hot water taps are a little stiffer to turn after the change. Would this be down to increased pressured ?

 

[WaterTight]

Also, all the hot water taps are a little stiffer to turn after the change. Would this be down to increased pressured ?

Are you sure you've not just become paranoid? :stuart:

 

[WaterTight]

But if they are...yeah why not. Your hot will now be at mains pressure, nothing else can have changed. So, if they genuinely are stiffer, it's the only possible cause. Or a one in a million problem developing with valves of all hot taps simultaneously..

 

[AWheating]

its not uncommon to have a difference or even problems develope on hot water taps when you go from open vented to a combi. It can be very common for hot taps to get stiffer and even vibrate, this is normally more likely on taps that are old and insides have machanical worn.