Time to heat hot water cylinder

[MrTom]

The pipes are mostly hidden behind fitted wardrobes and under floors I'm not planning to re-carpet any time soon...

The HW tank was completely emptied this morning so I thought I'd check it's progress on heating up again this afternoon. After 105 mins of the boiler on at 70c flow temp, the copper cylinder measured around 40c under the tank thermostat. Pretty slow huh, or is that about right?

I expected more contact between tank and stat to be honest but it's just conducted through the metal frame that the stat is mounted to, held in place with the tensioned chord around the tank.

I'm guessing as it's copper that the temp of the tank will be as near as damn it to the temp of the water inside? If not, should the tank thermostat compensate for the difference?

 

[JohnD]

that is curiously slow.

I have a modern blue one that heats in about 25 minutes from cold (though the modulating boiler throws more heat into it when fully cold, and adjusts its flame size down as the cyl nears the boiler flow temperature). You should see an appreciable difference between the flow and the return, when the cylinder is cold.

Are there any BS numbers or other markings on your cylinder?

An immersion heater (3kW) heats a cylinder at a rate of very roughly one litre per minute (it varies with incoming temp as the winter watermains are cold) and yours seems to be slower than that.

Post a pic of the cyl stat position and the flow/return pipes position.

 

[MrTom]

There is a torn old label on the cylinder which says 'Copper to BS2870' on it.

There is an appreciable difference in temp on the flow and return when the HW heating cycle first starts but after around 10 mins they are fairly close. I've managed to get a bit more of a temp drop by closing the return valve to 1/4 turn open (it was jammed fully open before).

I checked the temp again after around 2 hours and it was 46c. Curiously the stat seemed to think it had reached the right temperature as when I turned it up and then back down, it clicked somewhere between 50 and 60c. Something not right there!

Some photos, dunno why they are all in landscape view after I upload them:

Cylinder stat

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• MrTom
• 17 Jan 2015
• 1

Flow (top) and return (bottom) pipes)

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• MrTom
• 17 Jan 2015
• 1

Stat and pipes so you can see the relative positions

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• MrTom
• 17 Jan 2015
• 1