Immersion question

GHGW

So I installed a new 36 inch immersion with an 18 inch stat in my 42 inch tank with help from a plumber and electrician.

Previously only had at 18 inch immersion with 11 inch stat and never had enough water for two showers In our high pressure shower with amazon head fitted. Runs at 3 bar through a pump.

Was convinced I would have more hot water but doesn't seem to make a difference.

Have checked sink and bath settings in case they were wired wrong and no change either.

When I then Removed the stat to have a look it turns out its only 11 inches long but the sleeve it fits to into is 18. I specifically asked for an 18 inch stat and it took hours to fit the new immersion as there is no access above the tank so it had to be disconnected and leaned out. To now fit an 18 inch stat I will have to lean it out again.

Question will the immersion only heat water until the stat tip end reaches the desired temp?

and at that stage should the water below be as hot as above the stat considering the immersion runs all the way down to 36 inches? Or only hot from the stat tip up to the top of the tank?

Is it worth fitting an 18 inch stat?

Any help appreciated this is driving me mad

corkgsxr

You should get full heat to depth of element

GHGW

Thanks any idea why it's not heating down to 36 inches?

I did notice that the home heating coil upper attachment about 14 inches from top of the cylinder is roasting hot is this normal? Lower one is cold

Pipe at top of tank is also roasting.

corkgsxr wrote: »

You should get full heat to depth of element

corkgsxr

Any chance your getting parasitic circulation off the coil

GHGW

Can you explain what that means and how to check.

Would I be correct in thinking it involves the coil heating up and circulating down to the heating manifold behind my indoor boiler and stealing the heat from the immersion?

corkgsxr wrote: »

Any chance your getting parasitic circulation off the coil

shane0007

Before going to all the trouble of trying extremes, why not look up what the flow rates of your shower head is at the given pressure.
A 42" x 18" cylinder has a volume of 144 litres. A standard power shower has a flow rate of about 15 litres per minute so a 10 minute shower would be 150 litres. This would be about 60% hot so about 90 litres from the cylinder. So not enough to get 2 showers!
If your has a large head & with a 3 bar pump, it could well have a much higher flow rate, in the region of 25 litres per minute.

GHGW

Thanks Shane.

I see your point but when we have the heating on in winter we have plenty of hot water for two showers from the tank as the coil heats from the bottom.

It is only a summer issue when heating is not on so I think it's an immersion issue.

Also I had it on for four hours and it only filled the bath about 3 inches when I tested it but in winter it's enough to fill it for a bath when the heating has been on and its a large bath. So capacity doesn't seem the issue.

Any other ideas.

Is it normal for the central heating coil to be roasting hot when only the immersion is on? Just checked and the top outlet pipe and the upper central heating coil pipe is roasting to touch but the tank is only warm down about 12 inches. Why won't the other 30 inches heat.

Had this problem for two summers now hoped the damn new long immersion would have fixed it.

shane0007 wrote: »

Before going to all the trouble of trying extremes, why not look up what the flow rates of your shower head is at the given pressure.
A 42" x 18" cylinder has a volume of 144 litres. A standard power shower has a flow rate of about 15 litres per minute so a 10 minute shower would be 150 litres. This would be about 60% hot so about 90 litres from the cylinder. So not enough to get 2 showers!
If your has a large head & with a 3 bar pump, it could well have a much higher flow rate, in the region of 25 litres per minute.

shane0007

GHGW wrote: »

Thanks Shane.

I see your point but when we have the heating on in winter we have plenty of hot water for two showers from the tank as the coil heats from the bottom.

It is only a summer issue when heating is not on so I think it's an immersion issue.

That's because you probably have a 20 or 25kw heat source heating it for hours so you have a very good re-heat time. If you use the contents of cylinder, it will only take approx 25 mins to have it hot again.

shane0007

Another check is to turn off the valve feeding the cylinder & heat to see if the issue is resolved. If it heats with the cylinder feed off, then you have a leak somewhere on your hot water pipe work drawing all your hot water off. If doesn't need to be much of a leak to siphon the heat from the cylinder.

GHGW

Thanks Shane so close the hot water outlet from the tank and see if it heats the full tank if it does then there is a leak. I see how this works will try tomorrow.

Regarding the heat source...CH coil vs immersion ...filling the bath only takes 5 mins with the pump we have so quick reheating due to using the central heating coil I don't think is the reason we have water in winter and not in summer when using the immersion.

It has to be a leak or immersion problem or as cork mentioned parasitic loss no idea what that is though.

Very frustrating.

shane0007 wrote: »

Another check is to turn off the valve feeding the cylinder & heat to see if the issue is resolved. If it heats with the cylinder feed off, then you have a leak somewhere on your hot water pipe work drawing all your hot water off. If doesn't need to be much of a leak to siphon the heat from the cylinder.