Hot water tank reheat time..

So may last year I had a new intergas eco RF 24 installed with evohome opentherm controls, and hot water priority 3 port valve.

I set the timer to heat the hot water twice a day and have it on for 2 hours each time to account for the water we use.

However over Xmas our timings we're all out and I needed to re-heat the tank a few times.

At first I used the boost function on Evo home, but after about half an hour the water temp hadn't even risen 1 degree but the boiler was running though the pipes in and out of the boiler were only warm.

Eventually and 20 minutes later the water temp did start to rise significantly and another half hour later the water was hot the wife wasn't exactly happy how long it took as she wanted a relaxing bath.

Then couple of days later same thing but this time I used the timed function not the boost, the hot water came on quicker, but still took best part of an hour to get upto full temp.

Info on the cylinder it was replaced in 2010 by previous owners, it's a
117 Litre Vented Hot Water Cylinder (900 x 450)

Can any of the experts explain what may be happening?

The installer did offer to install a high gain cylinder from the intergas shop but I didn't have the additional moolah at the time.

Thought I'd update this.

Had the 1st year service the other day, spoke to the heating engineer and he said it was odd and he'll look at it.

He switched the heating on and confirmed my findings.

He then remembered he range rated it down to 5kw to stop the boiler from cycling as it was only doing the hot water cylinder, and he thought it would only have a 3kw coil in it, but the problem was too much heat was being absorbed from the boiler flow by the tank and the range rate wasn't powerful enough.


It's now been adjusted to 15kw and heats the tank from cold to hot in 30-40 minutes.

Pity you did not ask the installer when you first encountered the problem!

If he had been awake then he might have immediately realised what the problem was.

Agile said:

Pity you did not ask the installer when you first encountered the problem!

If he had been awake then he might have immediately realised what the problem was.

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He's very busy and I don't like disturbing him. As said I could live with it, so it wasn't a massive issue.

sxturbo said:

He's very busy and I don't like disturbing him. As said I could live with it, so it wasn't a massive issue.

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Was it Dan?

Sounds to me as though the flow a return are going to rads and HW cylinder both, but the rads are taking away most of the heat - once the rooms warm up and the TRVs close off, the water is force more to the cylinder. Whether is a control problem or a valve problem is yet to be determined.

Does it also fail to work as expected on a hot summer day?

Nozzle

dilalio said:

Was it Dan?

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No wasnt dan was a friend of his, same surname though, lol

Nozzle said:

Sounds to me as though the flow a return are going to rads and HW cylinder both, but the rads are taking away most of the heat - once the rooms warm up and the TRVs close off, the water is force more to the cylinder. Whether is a control problem or a valve problem is yet to be determined.

Does it also fail to work as expected on a hot summer day?

Nozzle

Click to expand...

its always worked, just took a long time to heat up.

the rads never get hot when its just calling for hot water.

it transpired the installer range rated the boiler to its minimum when hot water was called for, this was done in order to minimise boiler cycling, this meant only 5kw of heat was being produced, and the coil inside the cylinder was extracting pretty much all of that heat.

a simple increase in the range rate from the boiler was all it required,

as agile said i should have just called the installer, but i didnt want to disturb him as i know he's very busy and tbh it wasnt really a huge issue, was only an issue when we were having the odd lazy days which meant the hot water was off at the time of showers etc and we wanted to use the boost function, to ensure the water was hot for when we get up i just set it for 2 hours earlier than needed.

my initial thoughts were it was the hot water cylinder on its way out and needed replacing, thankfully it is and was a simple adjustment.

sxturbo said:

No wasnt dan was a friend of his, same surname though, lol

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Dean then.

Same forename as me!

dilalio said:

Dean then.

Same forename as me!

Click to expand...

Ah you know him, wasn't sure you would.

He's a top bloke.