Range flowmax thermal store.

[Jolead]

Evening

Ive got a customer with a range flowmax.

The customer is saying that the hot water is hot but only for 1 shower but before they would get three. There is one immersion at the bottom on economy 7 with a boost. Its a vented thermal store. At first i thought the blending valve is playing up but why is the first shower ok? Any got any ideas.

Cheers in advance

 

[townfanjon]

The way a TS is designed it will not perform well in winter , store temp before it gives HW has to be 75 degrees , what is the store capacity ? Make sure the header tank is around half full . Mixer valves are a fortune for them and hardly ever need changing . Make sure the pumps not knocking off after the first shower , rare but it happens .
I was a Range engineer for around 6 years , I know them inside out .

 

[Jolead]

The way a TS is designed it will not perform well in winter , store temp before it gives HW has to be 75 degrees , what is the store capacity ? Make sure the header tank is around half full . Mixer valves are a fortune for them and hardly ever need changing . Make sure the pumps not knocking off after the first shower , rare but it happens .
I was a Range engineer for around 6 years , I know them inside out .

Similar to an electric shower? Incoming mains being very cold?

It's a 1730 by 450 so a 210 litre. I only have pics to go on for a regular customer. Mixer valve on line looks to be £110. Customer said header is at least a 1/3 full bull valve operates. It's economy 7 with storage heaters so are you saying the heating pump knocks off? Don't understand that. What I have noticed is they seem to have a normalntesla stat which the over heat is at 70. Do these need a manufacturer stat? Is this the issue?

 

[townfanjon]

Yes exactly same principle as a lecky shower.
The big problem with them is the stats , what they say and what they heat to can be 20 degrees out , it wants the right stats pal , overheat should be 90/95 .
I used a combination of stats , one quality control stat and a separate overheat but it depends how far you want to go . I maybe wrong but I really doubt the genuine mixer is £110 , but get the store to temp first .
If it goes cold on them and the cylinder is still hot , just check the pump is still running and the red light is on .

 

[Jolead]

Yes exactly same principle as a lecky shower.
The big problem with them is the stats , what they say and what they heat to can be 20 degrees out , it wants the right stats pal , overheat should be 90/95 .
I used a combination of stats , one quality control stat and a separate overheat but it depends how far you want to go . I maybe wrong but I really doubt the genuine mixer is £110 , but get the store to temp first .
If it goes cold on them and the cylinder is still hot , just check the pump is still running and the red light is on .

Ok mate thanks for your help. The mixer may well be a monkey one not sure. I think the customer wants to change it for a unvented cylinder anyway so ill bring it home and have a play with it....

Cheers

 

[townfanjon]

Yep most want to go down the unvented route , but ask yourself this,
“ why wasn't there one there in the first place “ ?
9 times out of 10 its the discharge pipe .
Presume this is in an apartment

 

[Jolead]

Yep most want to go down the unvented route , but ask yourself this,
“ why wasn't there one there in the first place “ ?
9 times out of 10 its the discharge pipe .
Presume this is in an apartment

Yes the usual problem. It's got an fe tank on top so there must be an overflow. Was hoping it's in copper as per the mi's so was going to use that if possible. If I can't find a route what would you recommend replacing it with? Yes it's an apartment

 

[townfanjon]

It will have an overflow but it will be plastic and probably go into more plastic , if you can find out the manufacturer of the soil pipe and its suitable to take the discharge thats where you can go .
IMO , its risky, but not out of the question putting an unvented where a thermal store used to be.
Replacement TS , I generally fit the Aquanox but expensive.
I wouldn’t go down the replacement route yet , Flowmax’s are absolutely fine until they leak , and then its a new one .

 

[Jolead]

It will have an overflow but it will be plastic and probably go into more plastic , if you can find out the manufacturer of the soil pipe and its suitable to take the discharge thats where you can go .
IMO , its risky, but not out of the question putting an unvented where a thermal store used to be.
Replacement TS , I generally fit the Aquanox but expensive.
I wouldn’t go down the replacement route yet , Flowmax’s are absolutely fine until they leak , and then its a new one .

Right ok. Mi's on these say overflow should be copper but yes it's probably plastic.
Thanks for the advice I'll update thread when I fix replace....

All the best

 

[Jolead]

Guys I thought I would update this thread and pick brains at the same time.

When I visited the property before I got to the actual issue I found the immersion live terminal was broke off and the customer had just wrapped the wire round the broken pin and put a small crocodile clip to hold it on

Unit was old and it was a ground floor flat and I found a route under kitchen cupboards for a 22mm copper overflow so I fitted a kingspan unvented.

Anyway whilst there the cylinder had actually warmed up to 75 degrees via the immersion despite the suspect live terminal.

I then had a little play with this at home to diagnose the issue.

I warmed the cylinder to temp, attached temp guage clip to hot out of blending valve. Incoming mains temp was 6 degrees.

I set the oventrop blender to max and installed a lever valve to cold main in on blender to close (if blender faulty I could close and performance should improve)

On opening hot tap my initial hot water temp was 51 degrees.
After running 1 showers worth of hot water (50 litres) it dropped to 46.6

After running 100 litres the hot water dropped to 38.5 degrees

After 150l it dropped to 33 degrees.

Does anyone know if this is correct on this type of unit. Can't find heat loss calcs anywhere. Looks ok to me so I'm suspecting someone had played with the mains stopcock.

Shutting the lever valve increased temp by around 1 degree so it wasn't the blender at fault.

Thanks in advance