Hot water problem, please help!!

[kidgreen61]

My money is on a simple airlock, as said above, forcing mains cold through the HW system will clear it.

 

[Laurieo]

If its a mixer put your hand over the outlet, open the hot tap then open the cold one ,adjust your hand's pressure so the cold flows up the hot side .
Try this a few times should force mains pressure through the hot system .

 

[Hugh Jaleak]

Yes, sorry I should have elaborated. The how water comes on instantly, as normal in the downstairs bathroom.

In which case the flow from the Hot Water Cylinder is fine, so the problem is elsewhere. As said, air lock would be initial suspect.

 

[HomerJay99]

My daughter just reported that the hot water in the kitchen started working again suddenly but is now taking around 20mins to start flowing. No one’s touched it as it’s Sunday, feels like the plumbing god is fu**ing with us and having a laugh.

 

[Johntheo5]

Does the kitchen mixer have two separate taps, or is it a single lever type mixer?,

Does the HW come off the very top of the cylinder or is it at the side of the cylinder top?.

 

[dilalio]

It is air.
But it is repeatedly finding it's way back into the pipework after use of a tap.

So, my "at distance" diagnosis would be that water is back flowing, away from the tap, probably by opening a tap that is lower down and is pulling water out of the pipework, before drawing it from the cylinder. This is likely down to poor pipework runs.. A non return valve in the right location(s) might sort this.

 

[JohnD]

You mentioned that the loft hatch is very narrow.

Is the plumber too fat to get through it?

 

[HomerJay99]

He's not fat - it's just stupid small! Seriously it's around 14" square and I have no idea who the hell can fit through that other than a small child! We looked at increasing the size of it but its that size because the joists are that far apart! Its an old bungalow that's been converted to have an upper floor at some point in the past.

 

[JohnD]

You need a competent carpenter as well.

 

[dilalio]

He's not fat - it's just stupid small! Seriously it's around 14" square and I have no idea who the hell can fit through that other than a small child! We looked at increasing the size of it but its that size because the joists are that far apart! Its an old bungalow that's been converted to have an upper floor at some point in the past.

A Joist can be cut and braced to the joists either side... In most instances.

 

[HomerJay99]

OK, just an update. It turns out that because this was a bungalow originally, for some reason there wasn't the space to add a full size tank in the attic, so they added 4 or 5 (!) smaller tanks instead which are not providing the necessary pressure to the system. Apparently what needs doing is to add a 'booster' to the system which will give us the necessary pressure to simulate a large, normal tank. Hopefully this will help.

 

[JohnD]

A lot depends on your roof shape. Mine is pitched steep and there is a platform mounted one metre above the loft floor with a large tank on it. With high ceilings this gives a moderate flow to the second floor shower.

You can get special tanks designed to poke up through a loft hatch, but the time to look at that is when you have a carpenter in to enlarge your hatch.

Plastic tanks are somewhat flexible on a warm day.

 

[Madrab]

they added 4 or 5 (!) smaller tanks instead which are not providing the necessary pressure to the system

Unfortunately whoever told you that is talking nonsense I'm afraid.

Gravity systems work by head of pressure and that is dictated by the height of the cold water supply above a given outlet. As in your bungalow, any normal gravity system has the cold water cistern in the loft, some are even just above the cylinder in a top hall cupboard, several cisterns rather than one, doesn't alter that premise. Therefore the pressure of water at the outlet is dictated by the height of the cylinder above it. That can be as little as 1m (0.1bar) or even lower, as in the case of a bathroom shower or up to 3m at the downstairs outlets (0.3bar). Of course the pressure will be low and can sometimes be a problem if the pipework isn't correct and the pressure isn't great enough to overcome airlocks in the system but that isn't why your system isn't working properly. There are 1000's of systems like yours that work perfectly fine and it's usually isn't until some inexperienced person comes along and alters/adds things that it starts to cause problems.

Yes pumping the system might be a solution but if it is airlocking all the time, then a pump won't sort it, in fact it could seriously damaged the pump if there's lots of air passing through it.

As has been suggested, there is something not right with the design of the system and that needs to be corrected first, that needs someone that is experienced with gravity systems.

 

[HomerJay99]

Thanks.

 

[Madrab]

Thanks.

Given your reply, I do appreciate that's not what what you want to hear. It can be a little demoralising when other information doesn't tally with what you believe to be a professional opinion on your issue. Honestly I don't say these things to annoy, as a professional that has experience in these types of systems, I can only give you the benefit of that experience. It gets really annoying when supposed professionals give clients really duff information because it sounds right and we have to burst that bubble.

They may come along with a pump and it may sort it, at least in the short term, but that isn't a proper fix for what your system needs. Your system should work quite happily and it doesn't. The one and only real reason an (expensive) pump should be added to a gravity system is to increase the pressure and flow, say for shower etc certainly not to try and fix flow/airlock issues.

Also, is it going to be a dual pump where both gravity hot and cold supplies are pumped? If not then there may be further issue, where the gravity cold water is affected if the hot is pumped and it's then mixed.