Low flow

[Marvelous]

Evening ladies and gents,

I have a bit of a quandary. A customer of mine has recently had a conversion done with a new 210l Megaflo. All was well for the first 2 years, but has noticed a reduction in 'pressure'. After testing the pressure (2.8 bar) I noticed a dramatic fall in flow rate to 8l/m (these were measured at shower outlet (without shower head of course) and basin. Limescale build up on shower head was terrible.

I thought that limescale build up could be the problem. How do you solve that in a large setup with a mix of old and new pipes. I don't want to start digging around unnecessarily.

One other thing, the supply is just 15mm. With 3.2bar at nearest outlet.

 

[kettle1]

does it have a blocked filter on the inlet side?

 

[Marvelous]

Did not notice any filters on mains water supply or pipework to and from cylinder.

This problem is common throughout. Hot and cold outlets. It it more noticable from the hw though.

 

[AlanE]

Did not notice any filters on mains water supply or pipework to and from cylinder.

Standard fitting. But you would no doubt know that if you were qualified to install/repair unvented cylinders.

 

[Marvelous]

Hi AlanE,

No I am not certified for unvented cylinders, but it stands to reason as there are safety valves. I just do the pipework and get someone else to install and commission. Saves me time and money.

If it were the filter? Why would it effect the cold water system? 2 Blockages?

 

[Gasguru]

Have you checked the boundary stopcock is fully open?

Measure the flowrate at ground floor level, if less than 9 litres/min at 1 bar then call out the water company since below the legal minimum.

Unfortunately they often work to the legal minimum even if they block up the stopcock after roadworks.

 

[Fluffster]

Some Prv,s have a built in strainer so check that too.

Pete

 

[AlanE]

If it were the filter? Why would it effect the cold water system?

It forms part of the combination valve. Part of servicing of an unvented cylinder is to check/clean this filter.

If the cold water system has been connected as a balanced cold water one then the take off for the cold would be AFTER this combination valve assembly.

Do they have an outside tap or main sink tap connected to main supply? If so check here for pressure & flow. Main stop valve could have also shed its washer and reducing flow.

 

[Marvelous]

Geez guys, so much to get stuck into for monday.

Either way, I will probably start at the stopcock and work away from there.

You guys are an awesome source of knowledge. Keep up the good work and I will keep you posted.