Is it safe to leave central heating system empty?

[semolina]

My central heating is an open vented system and is about 35 to 40 years old. It has been cleaned (with Fernox F3) and then drained down, so has been empty for some months now. I'm thinking about leaving it empty and unused over summer (I wont be needing any hot water from taps over that period).

I would like to know if it is safe to leave the system drained and empty. I presume there wont be any corrosion since there is no water in the system but could anything else undesirable happen if the system is empty for a prolonged period?

 

[heatservice]

What boiler have you got? You shouldn't have any problems with your system but some boiler years ago which has rubber gaskets on the manifolds were prone to leak if left for a few months drained down.

 

[semolina]

Hi, thanks for the reply. I've got a Glow-worm Space Saver 50 MkII.

 

[heatservice]

Hi, thanks for the reply. I've got a Glow-worm Space Saver 50 MkII.

They were a good boiler in their day, I had one myself, if I remember rightly they had paper gaskets on the heat exchanger side plates, never came across one that leaked.

 

[Dan Robinson]

I would be concerned about prolonged exposure to settled water in the rads causing rust. You won't have got every last drop of water out.

 

[semolina]

I would be concerned about prolonged exposure to settled water in the rads causing rust. You won't have got every last drop of water out.

Ok. Maybe would be safest just to refill the system now, then. If I refill now but am not using the system, could the motorised valve start to seize up?

 

[Dan Robinson]

Unlikely if turned off.

 

[heatservice]

Ok. Maybe would be safest just to refill the system now, then. If I refill now but am not using the system, could the motorised valve start to seize up?

How long are you talking about as many systems go 6 months without the motorized valve operating.

 

[semolina]

Unlikely if turned off.

Ok. I ask only because the synchron motor failed once before after the system had been left unused (but filled up) over summer. So if I refill but leave the boiler turned off, that should be safe (pilot light doesn't need to be lit)?

 

[heatservice]

I Remember many boilers that were not used in the summer months suffer from a thick layer of fine rust dust on the burner top so make sure you get it serviced when its reinstated.

 

[Dan Robinson]

Ok. I ask only because the synchron motor failed once before after the system had been left unused (but filled up) over summer. So if I refill but leave the boiler turned off, that should be safe (pilot light doesn't need to be lit)?

It didn't fail due to lack of use.

 

[semolina]

How long are you talking about as many systems go 6 months without the motorized valve operating.

Would be (maybe) 6, 7, 8 months.

 

[semolina]

It didn't fail due to lack of use.

What made me suspicious on that occasion was that when using the manual lever on the valve (after the motor had failed) it felt like there really was a lot of resistance and I wondered if excessive resistance in the valve could have been the cause of the motor failing. Hence I made the connection that a lack of use can cause valve stiffness and a stiff valve can cause the motor to fail. But admittedly I was only guessing and know absolutely nothing about it.

 

[Hot&Cold]

if it is drained for an extended period,you might aswell extinguish the pilot light

personally,i would not leave that system drained (unless the property was empty with no inspection visits).

Its your call

 

[heatservice]

What made me suspicious on that occasion was that when using the manual lever on the valve (after the motor had failed) it felt like there really was a lot of resistance and I wondered if excessive resistance in the valve could have been the cause of the motor failing. Hence I made the connection that a lack of use can cause valve stiffness and a stiff valve can cause the motor to fail. But admittedly I was only guessing and know absolutely nothing about it.

Probably wouldn't make any difference if system was drained or not, valve might get tight due to lack of use long-term.