Hot water not staying hot, secondary return without pump fitted.

[kate66]

I am at my wits end. We have a Centre Store 300L solar tank. We have not fitted the solar yet, that is for the future. When it was installed, the plumber appears to have plumbed in all the secondary return but there is no pump, so I am assuming that it is not used. However, if we heat the tank of water in the morning and not switch on a single tap, by evening the water is cold. If I touch the copper pipes that go into the "primary return" and the "secondary return" they are both hot, so I have to assume that for some reason there is hot water going out into the pipes even though there is no water running?

So, couple of questions:
- would getting the secondary return pipes taken off the tank make a difference? (is that even possible after they have been put on?). I have no idea why the plumber put on the secondary return and all the associated plumbing, but when questioned months later he admitted that the pump wasn't there and refunded me the cost of the pump.

- when should I feel the primary return pipes hot? (For example, I just put on the hot water and within seconds I could feel the primary return pipe get hot)

Thanks. I know nothing about any of this but am just so frustrated and spending money to constantly heat water again and again.

 

[SimonG]

Welcome along

Some pictures of the installation will help.

 

[kate66]

Thank you Simon, let me go and get one

 

[kate66]

Tank, with primary and secondary returns fitted and then a whole wall of plumbing

 

[SimonG]

Needs that secondary return doing away with. Looks like you are getting a gravity circulation through the hot water feed back to the return.

Would also want the isolation valve taken out of the cold feed as it is after the expansion vessel. Also the one on the hot at top of cylinder.

Should all be insulated.

Be interesting to know if he was qualified to install and if you have received your certificates from local council.

 

[Dan-HybridHeat]

Seems like it could be that the solar coil isn't piped in. Basically the top coil is only heating up the top of the cylinder, and the stat at the top is being satisfied and turning off the boiler whilst the water in the bottom of the tank still isn't hot. During the day the hot water at the top will slowly mix with the cold water at the bottom cooling down all of the water in the tank.

The secondary return probably isn't helping either as the hot water will be rising up that return pipe and going to nowhere.

I'd recommend capping the secondary return and plumbing in the bottom coil as well so the whole tank is being heated.

 

[ShaunCorbs]

Needs that secondary return doing away with. Looks like you are getting a gravity circulation through the hot water feed back to the return.

Would also want the isolation valve taken out of the cold feed as it is after the expansion vessel. Also the one on the hot at top of cylinder.

Should all be insulated.

Be interesting to know if he was qualified to install and if you have received your certificates from local council.

+1 or a pump and time clock putting on it if its a big house

and bad soldering lol

 

[tolly]

View attachment 23707View attachment 23708View attachment 23709View attachment 23710

Tank, with primary and secondary returns fitted and then a whole wall of plumbing

Looks like a half decent installation other than there is a lever valve between then expansion vessel and the cylinder that shouldn't be there, i cant see a bronze pump for the secondary return but i can see check valve which would normally go between the pump and cylinder.

Can you not get original installer back?

 

[SimonG]

Seems like it could be that the solar coil isn't piped in. Basically the top coil is only heating up the top of the cylinder, and the stat at the top is being satisfied and turning off the boiler whilst the water in the bottom of the tank still isn't hot. During the day the hot water at the top will slowly mix with the cold water at the bottom cooling down all of the water in the tank.

The secondary return probably isn't helping either as the hot water will be rising up that return pipe and going to nowhere.

I'd recommend capping the secondary return and plumbing in the bottom coil as well so the whole tank is being heated.

I always pipe up the solar coil in paralell with primary coil until the solar is installed.

 

[AWheating]

the secondary return pipework should be lagged so well you wont really loose alot of heat from it.

 

[tolly]

I don't like the expansion vessel on a flexi aswell, hard pipe it. Change the stopcock for a lever valve, keep the lever valve on the balanced cold but do away with the one on the cold feed inbetween combination valve and cylinder as this could potentially isolate the expansion vessel.

Also Yorkshire fittings look messy, and it needs lagging.

I think weve all seen far far worse though, and i agree both coils need connecting until solar thermal installed, that's the problem, not anything to do with a secondary return.

 

[tolly]

the secondary return pipework should be lagged so well you wont really loose alot of heat from it.

helps if theres a pump on it though lol

 

[stevetheplumber]

if the secondary is running on gravity id leave it but get it lagged obviously at some point it was thought to be necessary and if its working without a pump bonus
or there must be fresh water motorised valve available to control it

 

[kate66]

Thank you everyone. There is no secondary pump installed and we do have to run the water for quite a while to get hot water upstairs. The house is a big old farmhouse and a decent distance to the taps, but I really didn't want a secondary system at all, so wonder if I ended up with half a system. I worry that there is hot water coming out of that pipe and just hanging around in the pipes in the walls? We had many issues with the plumber. The valve in one of the showers is the wrong way round so you turn it to cold for hot water and hot for cold water, the hand held for the overhead etc. Also, at least once I know that one of the toilet cisterns filled with hot water. Problem now is that of course all the floors have been laid, the tiling done etc etc. Thank you though, I will print this off and get someone else to come and fix it up.

 

[E4gas]

Cylinder stat should be at the bottom

 

[TVP&H Ltd]

Make sure whoever you get is G3/unvented qualified as it appears by the pics that your previous plumber wasn't.

 

[Chalked]

Just needs the bottom coil connecting in. You are only heating the top 1/3 of the cylinder.

 

[chris watkins]

This one wasn't signed off that's for sure.

Most got the isolation valve on the cold feed to cylinder which can isolation the vessel but also the expansion relief safety valve.

No one mentioned the balanced cold being taken off without a single check valve after the tee to stop hot mixing with cold, cos that will then mean moving the expansion relief safety valve & the expansion vessel con to the cylinder side of the check valve.

Who sized the cylinder? that looks like a non solar storage of no more than 100 Litres of hot water, this is never going to do you for the whole day - your choice until the solar is installed & heats more hot water.
1. As others have said pipe the solar coil & have 300Litres of hot water with all those standing losses.
2. Set timer so that boiler heats the hot water two or three times a day before it is required, lots less heat loss as less volume.

Either way insulate all pipework around the cylinder which should have been done under Part L when it was installed this helps with the heat being lost from the cylinder up & from the copper pipes that connect to it. (All the flow & return pipework should have been insulated)

OP state that they did not really want a secondary return but then say how long it takes & that the water goes cold in pipes the reasons why a property of this size & type would need one. Water Regs state HW at 50deg C should reach furthest fittings within 30sec to stop waste of water & energy. There are secondary circulators that provide closer control than just having them on a timer.

 

[Norcs]

Seems to be a valve on the secondary return. Could be a spring operated check valve.
It may or may not have a resistance high enough to prevent thermosyphoning.

If thermosyphoning is operating. Then you don't need a pump.
But perhaps a potable water valve that will shut it down at certain times.
Secondary return loops need thick 25mm wall armaflex insulation.

 

[Norcs]

This one wasn't signed off that's for sure.

Most got the isolation valve on the cold feed to cylinder which can isolation the vessel but also the expansion relief safety valve.

No one mentioned the balanced cold being taken off without a single check valve after the tee to stop hot mixing with cold,

I notice Megaflow make no mention of fitting an nrv on the balanced cold take off.

 

[chris watkins]

That would be because there would be no point in installing one, what would it achieve?

(Check valve goes on the cold feed to stop HW going back up the balanced cold take off)

 

[Norcs]

My apologies I thought you mean't fitted on the balanced cold take off.

Centerstores installation manual shows the cold water combination valve as a two piece assembly with the balanced take off T fitted between the prv and expansion relief valve which houses the nrv on the inlet side.

But you fit that T your self. The oso combination valve has the balanced take off incorporated in the valve.