Dropping flow rates over time.

[JoeHill]

Hi folks.

I'm looking for advise for troubleshooting dropping flow rate that I could look into myself until we are up and running and I can get a professional in.

Over the last 6-8 weeks I've noticed that our water supply is dropping in flow rate and today I measured a tap running at 3.5 litres a minute whilst no other user was online.

We have an external tap that flows at +20 litres a minute and pressure of +4bar so I am confident it's not mains supply. (I'm rural so not got an immediate neighbour.
I've not been able to measure the pressure in the house but can only hold the pressure back with my thumb for about 10 seconds.

Some info
Single story cottage originally 1890 build but many changes over the years
External Worcester Oil fired boiler. for CH and DHW
I'm suspecting that the boiler is tripping on low flow when running shower, it's gone cold on 2-3 occasions.
Initially the tap runs fast but drops after a couple of seconds.

I am thinking I have a restriction somewhere that will need looked at. Does this sound right to the professionals?

Any insight appreciated

Cheers

 

[SJB060685]

External oil combi? Hard water area?

 

[JoeHill]

Correct Oil fired Combi. North of Scotland is soft water

 

[SJB060685]

Ok. So the outside tap is fine. Are both hot and cold suffering reduced flow in side the house? Do you have a pressure reducing valve on the cold main after outside tap?

 

[JoeHill]

Yes both taps. I have not found any pressure reducing valves and I sweated my erse of in the attic today following lines. Tomorrow I am going to look at what the flow is like at the filling loop point at the boiler.

 

[SJB060685]

If all taps are affected after the outside tap then I suspect there is something restricting them ie. a blocked strainer or similar

 

[EvilDrPorkChop]

Would agree with @SJB060685. If your outside tap is OK then it's obviously something after this, and tbh as he has said sounds like a faulty pressure reducing valve or strainer.

Is your outside tap on the same main as the house - as in the tap supply comes from within the property after the stoptap? Or is it feed from the cold supply underground before it enters the house.