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USA Unvented cylinder - water pressure

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Hi, looking for advice about unvented cylinder. I had one installed as part of a horrific modular loft conversion that was recently finished. The water pressure in the bathrooms is poor, probably worse than when just had combi and I cant use two showers/bathrooms at one time which was the point in having it installed. When first installed it seemed good but then there was a leak in the system. Leak was fixed but pressure now poor. The tested cold incoming measures at 22 lpm and 3 bar but when i check this in bathrooms its less than 8lpm. The plumber is refusing to return as loft company arent paying him(think theyre going under) and his only advice is that the incoming supply is the issue. Im not convinced though due to rate during test and i've recently tested outside tap and its 3 times quicker than inside. The new shower in loft occassionally has fluntuating pressure that you can see by eye. Does anyone have any advice?
 
I seriously cant believe this. Should i highlight anything other than the cylinder direction. He had discussed putting a pump on the cold water(under the stairs)? Is the pressure on outside tap good because all on 15mm pipe? If cylinder pipework was 15mm would it have been better pressure?
 
Is that a vertical Tempest cylinder that has been turned on its side and mounted horizontally?

If so, WTF???

Time to get a new, G3 qualified, plumber in to survey the installation and quote for fixing any issues.

I hope you haven't paid the loft conversion company yet... :-(
 
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He’s a cowboy. Should’ve done the cold feed right at the start. An accumulator or similar could help solve your problem but it certainly shouldn’t be at your expense. And no. Pressure and flow rate are key don’t drop to 15
 
Landmark lofts are the loft firm and landmark heating managed the cylinder installation. I dont think landmark heating are in trouble but think landmark lofts are. So incoming goes straight through house and under kitchen tiles. This and feed to cylinder(once correct) would all need to be replaced to get a good flow? The loft firms "engineer" that scoped the job and did pressure and flow tests never mentioned anything about incoming.
 
Well he clearly wasn’t qualified. He should as a minimum have tested static and dynamic pressure as well as lpm did he do any tests or just turn on a tap and say ooh that’s good
 
Easy way to test from the kitchen sink fill a 1l bottle and time it
 
I may be hedging my bets here but is there a chance that these cowboys have actually accidentally bypassed the cylinder and your hot water is all coming from the Combi still
 
J have done. Kitchen sink comes straight from boiler and hot is about 8lpm. Same as shower in loft. Test on outside tap is consistent with their test. Was definitely over 20lpm

Cold water test the cold please
 
I will get somebody onto it. What are the main risks of having it on side?

No warranty could split due to not designed for that

Have they allowed for the weight load in that area
 
It’s not installed to spec. It won’t heat correctly, your drawing off hot water from half way up so it won’t be hottest if cylinder is going through a reheat
 

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