Central Heating Mystery

[potatoman]

Hi, just bought a bungalow but can't figure out the lay out of the central heating. The system is open vented, as far as I can see there is only one zone valve, 2 port, which allows the water to the rads this is operated by the room thermostat.
At the time clock when the heating is selected nothing happens, the pump is not engaged so no heat at the rads.
When hot water is selected, the pump starts, so we get hot water.
When hot water and heating is selected we get hot water and hot rads, if zone valve is activated via thermostat

So i can't have rads hot on their own. Is this normal?

 

[heliotrope]

It would appear that you have gravity hot water and pumped heating.

What you describe is normal on this type of system.

 

[kris]

Hi there potato, its surely a fully pumped system with the pump coming on with hot water unless its gravity and theyve mixed up the 2 wires inside the timeclock numbers 1 and 4 ( 1 for ho****er and 4 for ch) is there defo not another zone valve near the hot water tank and is there a room stat ??

 

[potatoman]

It would appear that you have gravity hot water and pumped heating.

What you describe is normal on this type of system.

Thanks for your reply
Don't think it's a gravity hot water as the pump only comes on when you select hot water on the time clock

 

[potatoman]

Hi there potato, its surely a fully pumped system with the pump coming on with hot water unless its gravity and theyve mixed up the 2 wires inside the timeclock numbers 1 and 4 ( 1 for ho****er and 4 for ch) is there defo not another zone valve near the hot water tank and is there a room stat ??

Hi,
How can i tell if it should be a gravity hot water system,please remember it's a bungalow, tank nearly level with the boiler.
Good point about the wires being crossed, but that would only work if it defantly was a gravity system.
Looked and looked for another valve but no luck,what makes me think there is no other valve is that the pump does not work when only heating is selected
There is a room stat which operates the zone valve for the heating

Thanks for your reply

 

[kris]

Gravity hot water water via gravity , when you select hot water the boiler would come on with no pump and the water traveling to the cylinder would circulate via gravity, hot water rises to cyl then falls back to boiler , no pump used so when you said the pump comes on with the hot water it must be pumped, oh the pipes going to the hot water tank from the boiler would be 28mm bigger than the rest of the piopework,

 

[jtsplumbing]

Are you sure it's a 2 port valve ? Photo would help

 

[potatoman]

Gravity hot water water via gravity , when you select hot water the boiler would come on with no pump and the water traveling to the cylinder would circulate via gravity, hot water rises to cyl then falls back to boiler , no pump used so when you said the pump comes on with the hot water it must be pumped, oh the pipes going to the hot water tank from the boiler would be 28mm bigger than the rest of the piopework,

Thanks for that,
Ok so the hot water is definitely pumped ,if the hot water pipe work did have a zone valve on shouldn't the boiler have a by pass on ,which as far as i can see it has not.
I have been on google and cannot find a pipe lay out like mine unless the hot water is gravity feed,which it is not


So the question remains ,is my system normal ,as I can't have rads hot on there own,and if it is not normal is there anything I can do about it

 

[potatoman]

Are you sure it's a 2 port valve ? Photo would help

I will do my best

 

[Neil K]

Sounds like a mix up. Pump should only come on for CH or CH&HW if it's a gravity system

 

[kris]

Thanks for that,
Ok so the hot water is definitely pumped ,if the hot water pipe work did have a zone valve on shouldn't the boiler have a by pass on ,which as far as i can see it has not.
I have been on google and cannot find a pipe lay out like mine unless the hot water is gravity feed,which it is not


So the question remains ,is my system normal ,as I can't have rads hot on there own,and if it is not normal is there anything I can do about it

Not necessarily as you might have a radiator without a thermostatic valve which would act as a bypass. It will normally be the room that the room stats in. ( might be another room ).
Your systems maybe set up so hot water always comes on when heatings on and comes on when hot water only. I think you need to look at the clock or the wiring of the heating side . Depending on the make of the clock you can change settings inside the clock if you take the facia off the wall. There will be settings to change from pumped to gravity or vice versa.
Your pump should come on with heating only unless it's been wired wrong. You should check wiring and have a second motorised valve put in on hot water to give you full control and the choice to have each one on whenever you want .

 

[potatoman]

Not necessarily as you might have a radiator without a thermostatic valve which would act as a bypass. It will normally be the room that the room stats in. ( might be another room ).
Your systems maybe set up so hot water always comes on when heatings on and comes on when hot water only. I think you need to look at the clock or the wiring of the heating side . Depending on the make of the clock you can change settings inside the clock if you take the facia off the wall. There will be settings to change from pumped to gravity or vice versa.
Your pump should come on with heating only unless it's been wired wrong. You should check wiring and have a second motorised valve put in on hot water to give you full control and the choice to have each one on whenever you want

.

Hi,just checked the rads,they have all got thermostatic valve on,I am quite keen on putting a another zone valve in but will I need a by pass on the boiler

 

[kris]

yeh but the hot water coil would act as a bypass as theres no motorised valve onit which leaves it open for water to circulate ,

 

[kris]

If you installed another MV then youd need a bypass or make the rad in room with room stat the bypass,

 

[zzzjim]

How old is boiler ,as hot water is providing a safety feature ( That boiler may not have - if OLD )