Gas Back Boiler and Danfoss Timer

[JTSTAG]

Hello there.

I hope someone can help me out with a problem i have.

I have a friend who has moved into a rented property.All fine and dandy until it came to sorting out the heating and hot water.

A gas back boiler is fitted with a Danfoss FP715 Si timer/programmer,not a problem i thought as i have the FP715 too run my HW and CH.

I have reset the timer to 5/2 day with 2 on/offs per day,no problem.

Now comes the problem,the CH works perfectley,comes on and goes off exactly when it should.The HW comes on at the same time as the CH even though the timer says it should not come on.

The FP715 Si has on,off,auto and allday on the lcd display for both the CH and HW.The trouble is on the HW side the "off" will not work.If i press "select" to turn the HW off it does not let me have the option as it goes through on,auto and then allday.If i use the CH "select" button it turns off the CH and the HW.

Basically i cannot get the CH and HW to work independantly from one another.I am not taking the unit off the wall and looking at the wiring as with the property being rented i don't want to cause problems with the landlord,who by the way,hadn't got a Scooby about how the heating or hot water worked in the first place.

Now for the stupid questions.

Should the GBB/Timer be linked to a room thermostat like the Honeywell type that have a dial from 10 to 30 degrees.If it is,i can't find one in the house.

Are the thermostats/controls located under/behind the gas fire.

Having checked the Hot Water Tank,i can't seem to find the thermostat on it.I know what it is,what it looks like,where it should be and how to alter it,but i still can't find it.The tank is easily accessible and i have plenty of room to work in but i can't find it.

Could the FP715 Si be wired so as the CH and HW are on one channel as i seem to think that this could be part of the problem.

That's about it really.

Hope you can help.

 

[45yearsagasman]

You probably have a gravity hw system and therefore the two cannot be operated independently.Check out what other controls you have on the system ie any motorised valves etc.

 

[kevplumb]

if its a gravity hot water system
you cant have heating without water

 

[JTSTAG]

You probably have a gravity hw system and therefore the two cannot be operated independently.Check out what other controls you have on the system ie any motorised valves etc.

Where would i find the motorised valves.

How do i find out if it's agravity HW system.

Thanks for the replies.

 

[45yearsagasman]

Motorised valves are normally in the airing cupboard near the cylinder.
If the system is gravity hot water the primary flow and return pipes connectd to the cyl are usually 28mm or 1" in the old money.

 

[JTSTAG]

Motorised valves are normally in the airing cupboard near the cylinder.
If the system is gravity hot water the primary flow and return pipes connectd to the cyl are usually 28mm or 1" in the old money.

That's my job for tomorrow night then,looks like i won't be watching the football in the pub.

Thanks for the help 45yearsagasman.

 

[DP]

You are unlikely to have motorised valve on that setup. Pump only runs for CH, so there is no need for MVs

 

[OwainDIYer]

Even if the HW is pumped primary, it might not be set up for separate operation. On a mechanical programmer the sliders for CH and HW would be interlinked.

Typically these systems do not have a cylinder stat, relying on the boiler stat. They may have TRVs on all radiators, relying on the boiler stat for overall control.

The panel below the gas fire usually hinges off/down to provide access to the boiler stat etc.

They are very inefficient, but usually quite reliable.

As open flued appliances an annual safety check and adequate ventilation is essential.

 

[45yearsagasman]

Duplicated