Mains connection 15mm reducing flow?

[ecswtrav]

Hi All,

To cut a long story short I've a Ideal istor boiler I've posted abotu previously. Its an unvented cylinder all in one boiler. Bad reputation but mine has been good over the last 2.5 years. I had a new mains fitted a year back-ish and hoped for better flow rates. This didn't happen. Recently on here it was advised to look at the PRV which has since been replaced - a no difference. 8/9 LPM max even at the tap next to the boiler.

Anyway, I've since had a look at where the new mains comes in and it enters thee house on what seems to be a 15mm pipe. This then hits the stop tap and then the PRV and then continues on another 15mm pipe which is then within the ceiling. With the boiler being nearby the feed into that - which I can see - becomes a 22mm - so it must change behind the ceiling void. The pipes out of the boiler are 22mm .

Should the water entering the property on a new plastic pipe (with good flow I'd assume) be instantly restricted by a 15mm pipe? Isnt this going to substantially impact on the flow rates which is why my LPM is quite low?

I'm not expert but I'd love to get the flow rates up on the boiler. Ideal indicate up to 35LPM and 11 on an empty tank. I'm a million miles off that and with a new mains.

Thanks for you help

 

[Ch4 plumbing]

When you had your new water main fitted/upgraded did they spec a size?

If I run a new MDPE water main the min size for me is 25mm, no point in running smaller IMHO

 

[ecswtrav]

yeah its 25mm i couldn't remember the specific - thought it was 24/25/26 but it must be 25mm. think it was a blue or white pipe although I cant honestly remember

 

[AWheating]

sounds like the water supply in your area is pants or you have a leak near by underground. the wata board will give you around 9lpm min at the road side and around 0.9-1 bar.

if this is what you have outside you will need to boost the supply inside using some method.

 

[ecswtrav]

Using a gauge I measured the flow rate at the mains where it enters the house. There was no tap as such and instead I had to add a hose to what seemed like a drain off point. Right next to where the 25mm water pipe enters the house. this drain off point (sorry if thats not the correct terminology) was still restricted by a 15mm bit of piping...plus my hose pipe attachment. Anyway, I opened the tap to test using my pliers and it hurtled out. Easily in excess of 22LPM which is the maximum on the gauge. And not even opened the tap fully either as I didn't want to soak my basement area. So I'm getting great flow out of 15mm pipework right next to the mains, but once its passed through the PRV and travels down some 15mm piping to my boiler (via a stretch of 22mm piping) somewhere along the lines turns onto 8/9 LPM. If I put both the hot and cold taps on I get 15LPM or thereabouts.
It's my second PRV - this one being a JET one set at 2 bar - and still the same problem. I'm beginning to wonder whether the boiler is at fault but having said that its been like it since I moved in. Is it worth upgrading to 22mm pipe by the mains all the way to the boiler? I say that as clearly something is killing the flow rate and I'd assume it would be no different withh 22mm?
Thanks a lot

 

[Dsp]

I usually run the largest bore pipe I can and reduce where necessary so it would be 22 mm all the way to the boiler for me