Programmable HW Cylinder Thermostats?

[Kostas Kavoussanakis]

Hi,

Is anyone aware of programmable HW cylinder thermostats? If the price is right, I would not mid replacing my existing surface-mounting, temp-control only, cylinder thermostat. A 5/2 would be fine, a 7-d would be even better. My existing, 25-yo CH/HW programmer does not discern between days of the week; we therefore either have the HW needlessly on or run the risk of running our of HW. Because I have a programmable room-stat, I have no burning ambition to upgrade the main programmer (though I would not mind getting rid of it altogether if the HW could also be managed from its own stat).

The Danfoss WP75-RF would do it (if I had a matching receiver module), but it's too expensive as it does more than I need (wireless).

(nope, I am not holding my breath)

[Toby]

I think you really need to replace the programmer for one that will do both HW ancd CH seperatly!

I assume your system is fully pumped and you have either a 3 way valve or at least two seperate valves, one beinf for the HW?

Toby...

[Michael Chare]

I use a Danfoss TP9. This is a wired 2 channel programmer. It can be set for either a fully pumped system or one with one with gravity H/W.

[Dave Pickles]

I've been looking for the same thing.

25 years ago I designed my own microprocessor-controlled heating controller (and published the design in one of the electronics rags). There is nothing on the market now which comes anywhere close. For example to vary the temperature by programme - lukewarm for hand-washing, hot for baths and showers - or to make a tank of hot water then switch off and stay off even if the cylinder goes cold again.

Dave

[Kostas Kavoussanakis]

Thanks Toby.

I am not sure what "fully pumped" means. I have a pump (separate to my ancient, beloved boiler) that I hear when the CH is on; I am not sure it works when HW is on. I think my HW is gravity fed. I have a 3-way valve. As far as my Sangamo 410 programmer is concerned, I can have the HW and CH on "once", "twice" or "24h" independently of each other.

Replacing the programmer is beyond my DIY means; it is unfortunately buried in (imperial-size) tiles in my newly decorated kitchen, so it's not a straight-swap job. Maybe when the boiler dies, hopefully in

25-30 years or so :-)

Kostas

[Kostas Kavoussanakis]

Thanks, it (and its replacement, the TP9000) looks a good bet. But I am not able to replace my programmer with sufficient ease[1], and it would require that I chuck my programmable room stat.

However, this got me thinking: given that one has a programmable room stat and a cylinder thermostat, could they wire the CH permanently and use a cheaper 7-day, 1-channel programmer like the following exclusively for the HW?

still is not something that I could do myself, but thought I would ask, for education if nothing else.

Kostas

[SantaUK]

Can these sensors be fitted to tanks that need Probe-type Cylinder Thermostats? I have a Thermflow 210 vented and would like to attach a programmable thermostat.

[Michael Chare]

> It still is not something that I could do myself, but thought I would ask,

I can't see an logical reason for not having separate programmers if that is what you want.

[Clint Sharp]

In message , Dave Pickles writes

I've got around 25 years worth of the UK electronics mags so probably have this somewhere. I've been considering either retrofitting a simple thermostat with a small PIC and wireless module to make a simple wireless on/off controller and/or one of the larger PICs to make a programmable controller so any reference could be useful, especially if there's code with it.

I can imagine the one shot tank being very useful, overriding the tank thermostat to stop it turning on again would be an excellent way of preventing SWMBO WSIE putting the immersion on and forgetting about it.

[meow2222]

AIUI what's wanted is not varying temps but varying quantities of hot water. And there's a method out there to do this: With cheap rate electric systems, 2 elements are used, one short one at the top of the tank, and one full length one. The short top one produces a small amount of hot water rapidly, the long one heats the bulk of the tank up.

Your use of them would be a bit different to E7, arranging the bottom one to only come on when you wanted bath or shower amounts of hot.

NT

[Doctor Drivel]

A heat bank/thermal store can do that and quite simply too.

Luke warm for basins? A TMV on the basins. Or a line dedicated for the basin with one TMV for all basins

Another line for the rest of the outlets on a TMV

The shower directly off the cylinder and the thermostat on the mixer caters for that.

To heat a cylinder of hot water and then stay off? The Horstmann E15 Boost Timeswitch on

You press, the boiler stays on for the time selected, the cylinder turns off, then the timer expires.

[Kostas Kavoussanakis]

Thanks NT. No, I am not even looking for something as sophisticated as that (and I don't have cheap leccy, so I prefer to stick with gas). I am looking for a way to have hot water (perhaps more than I need) when I am in, while not running the boiler while I am not in.

I am in 3/7 days of the week. The easy thing with my current setup is to have the HW on 6:30-21:00, 7/7 and that's that. What I would like to do is have the HW on 6:30-21:00, 3/7, and on the other 4 days just have it on morning and afternoon that I am in.

What is happening at the mo is the timer is on the morning-afternoon setting, which invariably ends up either in a cold shower during the w/e or moving it to 24hrs on the weekday that we are in, then forgetting we have done this for a couple of months. :-)

Nope, this wife does not get the "advance" principle. :-)

Kostas (maybe I need a programmable wife? Or maybe I should stick it on 24/7 and stop worrying about it?)

[Dave Pickles]

Radio & Electronics World, July 1983. Good luck finding the parts, 256 BYTE memory chips will be rather hard to come by.

[meow2222]

If thats all you need, you can do that for a fiver with a plug-in mechanical 7 day timer. Add to it a little relay with 240v coil, making the switch contacts on the relay open the cylinder thermostat when no HW is wanted, and close for normal operation when it is wanted. And you can design it so the timer/relay section just unplugs, restoring it to conventional operation.

NT

[Clint Sharp]

Heh, not in my junk box they won't. It was also more about the code and program flow than actually building from a published design though.

Unfortunately I don't have a massive collection of R&EW from that sort of era anyway, I only bought the odd copy here and there and only started buying it regularly about 4 years after that.

[Doctor Drivel]

[Doctor Drivel]

[Doctor Drivel]

[Doctor Drivel]

[SantaUK]

Program my tank to call for more heat, such as 80 degrees in the morning, to allow for three showers each morning, and then at 10am to drop back to 60 degrees for day to day use. I dont think this type of tank stat will work on mine. No insulation to remove etc.