Is my flow rate any good?

[gdickin2]

Hi

Recently had a new boiler fitted - Vaillant Ecotec 937plus and the hot water flow rate seems crap (though probably a coincidence with the new boiler rather than it being the cause). I can not run the shower and any other tap in the house without the shower cutting off. Or any combination of hot taps for that matter - i.e hot tap in kitchen and bathroom on would cause a dribble from both.
As suggested elsewhere, I put a bucket under the kitchen tap and ran it for exactly 15 seconds - measured the volume of water passed and multiplied by 4 to get the /min rate. The hot came out at slightly over 10 l/min. Thought this was rubbish as according to the boiler lit. it can handle up to 20 l/min. Did the same on the cold water - mains fed, same tap - and got 14 l/min. I have nothing to measure the pressure with.

The house is newish - 10 years so all new (ish) pipework , and is on a new estate, so hopefully decent pipes to estate - but who knows!

I don't know what kind of flow rate I should be expecting on average and whether it will vary signifcantly during the day - i.e do I have to measure it at various times throughout the day to get an average?
Does the above flow rate sound ok, or do I need to hastle Untied Utilities - or will they fob me off?

Cheers

 

[gas4you]

It does not sound as if the cold mains flow or pressure was tested before you were advised a 937.

The 937 can supply 20 l/min for 10 mins, of hot water. As you have only measured 14l/min at the cold mains, you either have a problem (could be simply your main stop cock or water meter has not been turned on fully) or you have been mis-sold the 937.

For me to recommend a 937, I would be looking for around 25l/min cold mains and at least 2 Bar pressure.

 

[muggles]

Just out of interest, what did you have before? Did you have a combi or a system boiler and a cylinder? Just wondering why you feel you have a problem now but didn't before..

 

[gdickin2]

Just out of interest, what did you have before? Did you have a combi or a system boiler and a cylinder? Just wondering why you feel you have a problem now but didn't before..

Hi, we had a Gledhill Gulfstream 2000 described as a combined primary storage unit. It was a bit of a monster but gave good performance:
http://www.gledhill.net/pdfmanuals/2000 Range/GS2000-Iss8.pdf

I would have thought that if the Gulfstream worked ok then the Vaillant should do.

 

[mickyg]

get installer back, who in their right mind would walk away from a 937 with 10l/min peeing out. they weren't called john and wayne were they?

 

[gdickin2]

Installer came back last night and measured flow at ~22 l/min at the bathroom cold tap, but only 16 l/min feeding the boiler - which is odd as they come off the same branch upstairs! Flow seems to vary during the day.
He's going to have to come back and trace the pipes back to see if there is a blockage etc.