Anyone know this please?

[davethemuppet]

Hi all.

I have just bought a house which has a Glow worm Black gas fire with back boiler (I think a 45/2). Everything works, but I am a little confused over one aspect. I will try to explain

There is one controller, a Drayton TEMPUS 7. There is also one thermostat in the dining room. That is it. The controller (programmer) works fine as does the thermostat as far as I can tell. Here is my problem...

You can switch the controller onto 'boost' for either the hot water or radiators. When I do this for the radiators, they get nice and hot as you would expect. The water also gets hot? Which isn't really a problem. BUT, if I turn the boost on only for the water, the radiators all get hot. Not really what I want everytime I need some hot water only.

Now, is it just a case of turning the radiators all off? Is this normal? I have downloaded the manuals for both the boiler and the controller. I have sussed out that I have a pumped central heating with gravity fed hot water system, as opposed to all pumped. From what I can see it is all installed correctly and has been in for about 6 years.

I will eventually replace with a combi, but for now I want to enjoy what is otherwise a perfectly working and very quiet system.

Any help/pointers very gratefully received.

Cheers, Dave.

 

[Diyisfun]

Welcome
A little bump for your post, I am not a plumber.
I think you have a problem with a motorised valve.
The plumbers will soon be out of the cafe...

 

[45yearsagasman]

If you don't have any of these motorised valves then you probably do have a gravity hot system and the rads get hot due to a stuck or missing anti gravity valve.





View media item 30391 View media item 38425
This is a type of AGV View media item 38774

 

[Agile]

When you select just hot water then is the pump still running?

Tony

 

[ChrisOxford]

edit

 

[Whitespirit66]

If the hw works properly during it's normal on time on the programmer, but the rads come on with hw boost, then I am imagining that the anti-gravity valve is doing it's job. Sounds more like the pump is running on hw boost.

Programmer fault? You need to see if the pump comes on with boost hw.

 

[ChrisOxford]

If the hw works properly during it's normal on time on the programmer, but the rads come on with hw boost, then I am imagining that the anti-gravity valve is doing it's job. Sounds more like the pump is running on hw boost.

Programmer fault? You need to see if the pump comes on with boost hw.

Absolutely.

All the "boost" function does is switch the heating/hot water on for an (extra) hour or two, nothing else.

I presume the jumper on the back is set for gravity systems (not that a problem here should cause exactly your described fault).

P.S. Instructions for the programmer available here: http://www.draytoncontrols.co.uk/WorkArea/DownloadAsset.aspx?id=10467

 

[ChrisOxford]

If you don't have any of these motorised valves then you probably do have a gravity hot system and the rads get hot due to a stuck or missing anti gravity valve.

How do these AGVs work, please?

I always assumed that on this kind of system, the rads wouldn't heat up so long as the pump's not running.

Thanks.

 

[davethemuppet]

WOW!

Thanks for all the replies guys. I didn't expect anything like that many or that quick.

OK, to address some points. I haven't actually tried the programmer on timer at all yet. Just used boost for the radiators a few times, and a couple for some hot water. We have electric showers, so hardly use any hot water as such.

I am at home today, so as asked I just turned the HW on by boost and am just waiting for a few minutes to see if the CH pump runs.

OK, pump is silent but is running. There is an isolation switch for it and when I turn it off, the boiler shuts down. As soon as I turn it back on, the boiler fires up again. Also top rads are getting hot but downstairs ones are not?

I also had a look and cannot see an AGV anywhere, so I am now wondering if it is a pumped system after all? Would explain why the pump is on now, but if it is how is the HW and CH supposed to be seperated?

I will also have a look at the jumpers, but obviously now need to be sure what system I have. I have no reason to suspect the system has been wrongly set up for the last 5 years or so, but also have no proof that i hasn't - if that makes sense.

I VERY much appreciate your help guys.

Cheers, Dave

 

[ChrisOxford]

Look for a motorised valve, as 45yearsagasman said.

It could be hidden away somewhere out of sight though, of course.

Try following all the cables from the programmer (and any associated junction box) to see what they connect to.

 

[Whitespirit66]

How do these AGVs work, please?

I always assumed that on this kind of system, the rads wouldn't heat up so long as the pump's not running.

Thanks.

Used to be called a featherlight valve. Basically, when boiler only is on for gravity hw, the gentle thermo cycle of the rising water is not strong enough to push through the anti-grav. valve into the rad system. When the heating is put on, the pump is strong enough to push through the valve, and into the rad system where you want it.

Just a pressure valve, resisting gentle pressure, but allowing higher pressure from pump to pass through.

 

[45yearsagasman]

Very eloquent, couldn't have put it better myself

 

[davethemuppet]

I am now even more confused because having convinced myself it must be a fully pumped system, the programmer is set to pumped CH and gravity fed HW system.

IF that is correct, then I am guessing that there should be an AGV somewhere, but I cannot find one anywhere unless it is hiding in the loft. Would that be likely?

And why would the pump come on all the time then?

Cheers, Dave

 

[davethemuppet]

Bump?

 

[Hugh Jaleak]

Long shot but can you see the pipes coming from the boiler? Gravity HW/pumped CH will have 4 pipes, fully pumped only 2.