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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Plumbing Questions >> Drayton HTS3 Tank Stat problem https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1375515339 Message started by rgirling on Aug 3^rd, 2013, 8:35am

Title: Drayton HTS3 Tank Stat problem
Post by rgirling on Aug 3^rd, 2013, 8:35am

My original HTS3 failed, so I bought an exact replacement. There are only three wires to fit and - needless to say - the wiring anneals into shape and you can't really go wrong. Cover on, into insulation cut-out, holding strap applied and Bob's your uncle.

Trouble is, it doesn't control the temperature and seems to be running at 70ºC all the time, in spite of being set to <60ºC!

So, am I depriving a village somewhere of its idiot, or is there a simpler reason? I can feel an indent right at the lowest end of the scale - is that an "Off" position? I can't see what else I might have done wrong, but suggestions are welcomed and greatly appreciated.

Stumped. :(

Ray

Title: Re: Drayton HTS3 Tank Stat problem
Post by Lectrician on Aug 3^rd, 2013, 9:26am

When you turn the dial fully from one extreme to the other, do you hear/feel a click as the bi-metalic strip operates?

With the HW set to on, with the thermostat set to minimum, does the valve shut for HW? When moving it fully the other way, does the valve open?

Title: Re: Drayton HTS3 Tank Stat problem
Post by thescruff on Aug 3^rd, 2013, 10:13am

You have a p/on and p/off fully anti-clockwise is off and fully clockwise is on.

As above is the motorized valve, assuming you have one, opening and closing.

Some system info would be good.

Title: Re: Drayton HTS3 Tank Stat problem
Post by rgirling on Aug 3^rd, 2013, 4:45pm

The motorised vlve works as it should. I should explain a bit more:

Wife noticed that the hot water wasn't. I checked that the heating circuit was OK, then switched that back off. With the Hot Water on, as I moved the original thermostat higher, the boiler kicked in when nearly at max. I turned it back, but it went off before I got down to the desired temp, so I replaced the stat.

The boiler is a Potterton Prima and is what is known as a fully pumped system, I think. The hot water and heating circuits both have MVs and both seem to work OK.

Having replaced what I thought was a faulty unit with a new one - and matched the wires (I'm sure I got them right) - I was amazed that the water was too hot to use with the stat dial at <60 and now at <55.

Ray

Title: Re: Drayton HTS3 Tank Stat problem
Post by thescruff on Aug 3^rd, 2013, 5:04pm

60c would be too hot to use without dilution as will 55c.

Is the new stat making a good contact with the cylinder.

It would be natural for the new stat to work better if the old one was duff, so some improvement would be normal.

Title: Re: Drayton HTS3 Tank Stat problem
Post by rgirling on Aug 3^rd, 2013, 6:15pm

OK, thanks for that. I'll give it a while to settle down. I'm sure the contact with the tank is OK.

Ray