Hot water running low

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Hi,

We have just moved to our new house and we have a slight issue with showers.
The hot water runs very low on both showers, one at same floor of the hot water cylinder and one floor above it.

This is a Tribune HE Unvented Cylinder, connected to the boiler on first floor. As you can see in the pictures the heating pressure was zero (gauge under rend tank), which I brought to 1 bar by opening the valve on the re-fill loop.

What is the little white tank do. I read the manual online and seems like that the pressure should come from this unit.

I was wondering if someone could give me some help here, on what to do.

Thanks
 
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The white cylinder is an expansion vessel. Is the hot water coming out of the taps at good pressure ? Whats the make/model of showers ? Is your stop tap open fully ? (Open full then turn back a quarter turn). Cold water pressure ok ?
 
Hi and tanks for your reply

I have checked the main stop cock and its fully open
no problem with the cold water pressure anywhere in the house
the showers are just mixing taps (Thermostatic Shower Valve )
hot water's pressure is not that good even at the sink and wash basin taps

So would you confirm that the small white expansion vessel is for creating pressure in the tank?

Thanks
 
No the white tank isint to create pressure, if your cold water pressure is ok (and you reckon it is ) then the pressure reducing valve/strainer needs to be checked, thats the valve in your second pic.
 
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Hi hoss6800 welcome to the forum. Correct me if I'm wrong but that looks like you have moved into a new build property? I usually advise my customers to set the programmer for hot water to 'ON'. This allows the cylinder to run as a combi but allows a greater volume of hot water. The boiler will only run for hot water if the cylinder stat detects a drop in temperature. Those cylinder loose between 0.91 and 2.10 kW/Day (relatively negligible) through the insulation.

James.
 
Hi hoss6800 welcome to the forum. Correct me if I'm wrong but that looks like you have moved into a new build property? I usually advise my customers to set the programmer for hot water to 'ON'. This allows the cylinder to run as a combi but allows a greater volume of hot water. The boiler will only run for hot water if the cylinder stat detects a drop in temperature. Those cylinder loose between 0.91 and 2.10 kW/Day (relatively negligible) through the insulation.

James.

?
 
Hi hoss6800 welcome to the forum. Correct me if I'm wrong but that looks like you have moved into a new build property? I usually advise my customers to set the programmer for hot water to 'ON'. This allows the cylinder to run as a combi but allows a greater volume of hot water. The boiler will only run for hot water if the cylinder stat detects a drop in temperature. Those cylinder loose between 0.91 and 2.10 kW/Day (relatively negligible) through the insulation.

James.

?

My bad. Feeding the young un, I didn't read it properly.

To the OP, are you sure it's the flow rate that's a problem and not pressure? Try to run bath hot tap(s), kitchen hot tap and basin tap(s). Check flow rates are still adequate.

James.
 
Maybe my main question should be, is hot water systems pressurized or solely relies on main cold water pressure to push water out of tank.
 
It relies on mains pressure. It will have a pressure reducing valve set to 3 bar ish. Also has a filter. Some of the valve sets have a lever on them, check the valve/filter. There's only so much you can check, you may need a plumber with an unvented ticket.
 
Looks like the second cylinder this property's had, from what I can see.

Do you mean that the water outlets work OK individually but two showers are a big grim?

Chances are, you are running out of water. Unvented cylinders absolutely rely on water flow from the street, the equation is;

(A) Cold Water coming in from water main = (B) max water that comes out (hot and cold) through taps and showers

Therefore, if you open two taps simultaneously, the cold water main will be split across both and you will see a reduction in performance. If the water main is poor, both showers could drop to a dribble.

(B) can never be bigger than (A).

The expansion vessel (white) is where the expansion of the stored water in the cylinder when heated through circa 60C is absorbed; it doesn't augment flow, apart from for an instant when a tap is opened.
 
Hello guys and thank you all for your help and inputs.
Last couple of days I had a bit more time and do some more tests and find out what the real problem is.

It seems like that i made an early judgement saying the cold water pressure was good. After identifying that the main cold water run was not as good as i thought it was, i looked around a bit more to find out there is a PRV after the main stop cock.

It has "1 Bar" marked on it in red and not sure what level its set at right now as there are no gauges. there is a adjusting screw (needs flat head screw driver)

Any idea why they have put this PRV on the main cold water?

thanks
 

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