worcester 28i junior NEW low flow rate

[cdodds2004]

have fitted a a worcester 28i junior for a customer over the last 3 days removing conventional system, and coverting to a combi in the the utility room, used existing flow and returns for central heating and conected hot and cold into the pipes under work surface for utility sink, ran a new external 22mm gas supply, and problem with the flow rate of hw!

central heating working fine,

hot water only flowing at around 8litres a minute before a massive temp drop in the water so mixer shower in bathroom not working!

1st problem i found was main shower in bathroom was passing cold water into the hot pipe when hw demand on taps leading to only luke warm water, show isolated and all taps getting hw but only at around 8 litres a minute!

shower in en suite only getting luke warm at best due to low flow rate, did a gas rate and boiler was using 2.9m3hr which is withing tolerence of the 3.0 it states in manufactures instructions,

any advivce would be helpful,

boiler does sound like it is modulating and going on to full burn when tap is running! so i dont thing there is a problem with the flow turbine!

thanks people

 

[Blackcatgas]

the hot and cold feeds to the boiler are the wrong way round

 

[cdodds2004]

Are you sure???

 

[Blackcatgas]

Are you sure???

LOL!, are you sure you connected the hot and cold up the right way?

 

[Blake]

What is the flow rate on the incoming mains? Boiler spec states it should give out 11.4 l/min.

Any isolation valves on the cold feed to boiler that could restrict flow?

 

[cdodds2004]

well im 99% percent sure that i put the hot and cold the correct way around! tap was a mixer but i defined the cold pipe from the one feeding the washing machine and dishwasher and it had a blue iso tap on it! house has iso valves before each draw off! incoming pressure is high!

 

[Blake]

It's ok saying high flow but you need to use a flow cup to see where you stand. I would test incoming with a flow cup and also record incoming temp. Then check hot tap flow at all points and temperature achieved and compare to manufacturers spec.

 

[Blake]

Once you have checked all the above you can rule out low incoming mains pressure and/or poor pipework/fittings. Then you can contact Worcester to come out and take a look.

If you have not done all the above tests, they may charge you for coming out if it does turn out to be a non boiler problem.

 

[cdodds2004]

i will check the flow rate on the cold tap when i return to job next week, but can gurantee that the incoming mains is a high pressure, i didnt use a cup becuase i thought i was alot higher than most houses! only thing im thinking is were i conected into the hot and cold, there cold be iso valves on each pipe behind the cupboard backing! ie cold has to pass through a iso and hot has to pass through it again on the way out! could this affect the boiler to only have a hw flow rate of 8litres a minute!

 

[stevetheplumber]

have you checked the filter on the bottom of the turbine/flowswitch very easy to get a bit of crud or ptfe stuck in that. Easy to check as turbine is on two clips

 

[Blake]

There could be any type of valve behind the cupboard that could be restricting the flow. You could always cut the hot pipe below the boiler and stick a hose on and then into a flow cup, that would rule out a restriction on the DHW pipework.

Again, stick a hose pipe on the filling loop connected to the cold feed and test with a flow cup. That way you are testing incoming at the boiler and outgoing without any restrictions.

 

[cdodds2004]

yea will try that! to prove no restrictions and will remove turbine filter also before i think about giving worcester a call, thanks guys will give a update when i fix the problem next week!!!

 

[mickeyuk]

pressure and flow rate have nothing in common you can have a high pressure and poor flow!.Any 1/4 turn valves can reduce flow rate

 

[Kmort78]

Thats true, you may have 6 bar standing pressure but no dynamic pressure when runnihg from multi outlets

 

[cdodds2004]

ok guys thanks ill check get some investigation work done next week and let you no how im getting on