Is the 3.7 bar static, I presume? And is it measured before your pressure reducing valve (prv)? Sounds like your prv is set to 2 or 2.5 bar then? You will lose 1 bar for every 10m in height, so 1st floor will always be approximate 0.5 bar static less than ground floor. It's the dynamic/working pressure which is important, though - you should measure that whilst the tap which supplies 20l/min is flowing.
I still think (from what you said earlier) that you have a pipe restriction to the shower valve. Ideally, showers should be supplied with as much 22mm pipe as possible.
I still think (from what you said earlier) that you have a pipe restriction to the shower valve. Ideally, showers should be supplied with as much 22mm pipe as possible.
Yes, 3.7 was with everything turned off. If I turn on both showers and a few taps, the pressure coming into the house is 2.8 bar, but 0.7 at the shower.
I'll have to ask the plumber about the prv, not sure where it is, but I would think the 3.7 is upstream of it.
I'll get him to check the flow on the showers, thanks.
I'll have to ask the plumber about the prv, not sure where it is, but I would think the 3.7 is upstream of it.
I'll get him to check the flow on the showers, thanks.
That suggests either you do not have a pressure reducing valve (every Unvented Cylinder installation should have one!) or the prv you have is not drop tight, which means it will increase pressure under no flow conditions.
Excessive pressure will lead to premature failure of most shower valves. The warranty on them stipulates that the max pressure should not be exceeded.
Excessive pressure will lead to premature failure of most shower valves. The warranty on them stipulates that the max pressure should not be exceeded.
I've found the prv, its in the airing cupboard, a Heatrae Megaflo. If it were causing the 7.9 hot in the morning, wouldn't I also have 7.9 cold? I am not seeing that, the cold never goes above 2.4.
BTW as soon as I turn on a tap or the shower, the 7.9 drops to ~2.3 for the day.
I think I'll leave it to the G3 certified plumber to figure out, but very interesting, at least I have some data for him.
BTW as soon as I turn on a tap or the shower, the 7.9 drops to ~2.3 for the day.
I think I'll leave it to the G3 certified plumber to figure out, but very interesting, at least I have some data for him.
I missed that it's only the hot. That means the pressure is rising because of the expansion of hot water whilst the tank is being heated. You need to replenish the air bubble in the megaflo tank. Instructions are on the side of the cylinder.