any plumbers or heating installers here ?

dUnKle

Member
Sorry for yet another thread related to my new home purchase

Having problems with the central heating - can not get in touch with the sellers for explanation and can not find instructions on how to get the system working

The system in question is a Randall 702 - which I belive is by a company called Danfoss Randall and is around 15 years or so old

Its the timer type box I am having problems with - it works fine but just cant work out how to get the water and heating to come on when I want it to (and also how to get the water to come on at a different time to the heating etc)

At moment have worked out how to switch it on and off manually but would like to use the timer function

So if anyone out there has a .pdf of the manual could you give us a shout
 

IronGiant

Moderator
Can you post up a picture, then someone may be able to suss it out for you if no-one can find a manual.

dave
 

dUnKle

Member
Ok

here goes - possibly the least interesting photo ever



There are some very basic instructions on the flap but they relate mainly to settings and even state at one point to refer to instructions :(
 

IronGiant

Moderator
I wonder who designed that, it doesn't look very end user friendly does it, no wonder you're stumped.
 

Chris Muriel

Distinguished Member
Blimey! Worse than a VCR menu then.
Is the "adjust periods" control for the females in the house then ? :D

Chris Muriel, Manchester
 

dUnKle

Member
I read the first post and laughed thinking how can you not know how to set a timer but after looking at the picture I reckon I would have to buy a new boiler:confused: :D
LOL

My Dad said the same

"its a timer - how hard can it be"

Took one look of it and started trying to design a time machine instead :)
 

IronGiant

Moderator
can you take a photo of the instructions such as they are.

Dave
 

T0MAT01

Novice Member
Ok

here goes - possibly the least interesting photo ever


(
Looking at that I'd say you've got 3 'ons' and 3 'offs' for each day, and it is up to you to determine whether they are used for hot water or heating or both.

On the top row is has buttons 1 - 6 with adjust periods written beneath, I guess you have to hold down one of the buttons and press the set time arrows until the red line is at the desired time and then you select hot water or heating to come on/turn off at that period by pushing the associated select button.
 

dUnKle

Member
Looking at that I'd say you've got 3 'ons' and 3 'offs' for each day, and it is up to you to determine whether they are used for hot water or heating or both.

On the top row is has buttons 1 - 6 with adjust periods written beneath, I guess you have to hold down one of the buttons and press the set time arrows until the red line is at the desired time and then you select hot water or heating to come on/turn off at that period by pushing the associated select button.
Well with the above suggestion and some messing about I have got it sort of working

Problem is though the heating always comes on when the water does :(

Even though the little light is off the heating switches on when the water starts to heat up :(

A google search brings up a similar problem with the following

It sounds as if your motorised valve may have failed!
and then

I dismantled the valve and found that there's a little black ball type thing that shuts the water off, this had come off the stem and was just floating free.
I've put it back on the arm and it's working o.k now.
So where would I find this "valve" and how easy is it to do ?
 

IronGiant

Moderator
I think we've discussed this one before, can you do a search on motorised valve and if nothing comes up we can run through it again.

Dave
 

961

Well-known Member
You're on a steep learning curve here, aren't you?

I went through the same thing ten years ago when I found that getting a plumber was impossible as they were all working for the local council on megabucks plus.

If you are having trouble getting the water and the heating to work independently then it may well be that one of the motorised valves has failed. However, you should also have a thermostat strapped to the side of the hot water tank and this may have failed or have been set at the wrong temperature. You can establish if this has happened by setting the programmer to turn the water on with the heating off and feeling the temperature of the pipes beside the water tank. Turn the thermostat on the tank up to max and see if you get the pipes into the tank hot and the pipes for the central heating radiators cold. Then turn the heating on with the room thermostat turned up to max and the water on the programmer set to off and the thermostat on the hot water tank set to max still. The pipes to the tank should then stay cold while the radiators get hot

I would say that in my book I wouldn't worry too much if you cant control the water on/off too much. It's the heating that costs the dosh. Establish if the thermostat on the water tank is working, 'cos that is easy to replace and won't cost much. Replacing a motorised valve will probably involve draining the system which isn't advisable at this time:) . Your better half won't thank you when the water and the heating go off and the plumbers have all knocked off until Jan 10th!

If the thermostat on the tank is ok just leave things until next summer when you can drain the system and sort it out without hassle
 

dUnKle

Member
God - why cant things be simple :)

The above helps though

Found the thermostat type thing, well I take it it is - its a circular dial on a square box - its down stairs in the hall

It was reading 30 so I turned it all the way down - however still get the same problem - water AND heating coming on together

If I was to turn off all the radiators individually would this stop them filling up and stop the cost of filling them ?
 

neilmcl

Member
When you say heating and water are both coming on, is that all radiators or just certain ones, ie, upstairs only.
 

dUnKle

Member
When you say heating and water are both coming on, is that all radiators or just certain ones, ie, upstairs only.
Well - here in lies another problem

Its just the upstairs radiators - but only as the previous homeowners had turned off the downstairs ones at the radiators themselves as it is rather warm downstairs

However .... the problem comes that after getting the house we find that all the "knobs" (the white bits that go bottom white of the rads to turn on and off) have been lost by the sellers during the move

So we now have radiators upstairs that come on when the water does (even though on the controls above they are told to always be off) and no way of turning the radiators off til the "knobs" are found

Can these be purchased ?

I think the valve thing rings true - just wish I could turn the radiators off at forget about them - asume if we switch them off (if we aquire the knobs) then we dont pay to fill em
 

T0MAT01

Novice Member
I wouldn't turn them all off, sometime they can be used to disperse heat from the system to stop it from overheating. A radiator without a valve is usually the sign to look for.

You can usually test the zone valve manually using the little lever on the back of it, when you open it it should sound like a servo turning, then your pump should start up and then your boiler should fire. When you close it your boiler should stop but the pump may have an overrun to cool the system down.

The thing is there's a fair few different systems and if you don't know which one you've got then you may do more harm than good if you're not careful.
 

IronGiant

Moderator
I don't see the photo here? If it is central it is feeding hot water both ways. If you have the timer asking for hot water and central heating and turn the house thermostat right down (and the one on the water tank right up) it should move to the side that feeds the hot water tank. Turn the house one right up and the hot water one right down and it should move to the other side. Turn them both up and it will sit in the middle. If it doesn't do this then the motor has probably burnt out and on some units you can take this off and get it replaced without changing the valve (wet ) part. On some you can manually lock the lever to one side, which I think will give you hot water only, but obviously turn the central heating off at the timer if you do this as a temporary solution.

If the lever is moving as I described then there is probably a problem with the valve itself...
 

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