Is a combi boiler safe with NO mains cold water? (Urgent)

[Lycanfox]

Thanks in advance for any replies to this.

Basically this morning a hot tap would not turn off and was gushing hot water. I couldn't find an isolation valve for the tap so had to turn off all the water via the main stopcock. The only worry is a plumber I rung said that without the cold water going to our combi boiler, the heat exchange could melt itself and cause a lot of damage so we had to turn our heating off.

Now correct me if i'm wrong but surely as long as the hot water setting is turned off on the boiler, the boiler should have two different heat exchangers so the hot water one would not melt due to not having any water to heat if it was off, and the heating exchanger works on a closed loop so should also be ok?

Thanks again for any replies, the last thing I want is to destroy my boiler in such a cold winter.

Adam

 

[SimonJohns]

Depends on the boiler

 

[Guest123]

Hi and welcome to the forums. You should get a plumber out to fix your tap and then you won't have to worry about your boiler.

I normally switch all boilers off at the spur switch when turning off the mains water to a property.

 

[Lycanfox]

As far as I know it is a Ferroli Combi F30 D (I think). With a dual heat exchange for hot water and then for central heating.

 

[SimonJohns]

Just turn it off at the wall to be safe

 

[dancinplumba]

without stepping on anyone's toes you wont have a problem. it is safe and imo your plumber is wrong, do as system3 says andget a decent plumber to fix your tap

 

[Lycanfox]

He will be out tomorrow ASAP to fix the tap, I was just wondering for the moment.

What is a spur switch by the way? As Ideally I would like to keep my central heating on but the water off.

Hi and welcome to the forums. You should get a plumber out to fix your tap and then you won't have to worry about your boiler.

I normally switch all boilers off at the spur switch when turning off the mains water to a property.

 

[Lycanfox]

Tyvm.

Getting one out tomorrow morning to fix it....bloody old houses!

without stepping on anyone's toes you wont have a problem. it is safe and imo your plumber is wrong, do as system3 says andget a decent plumber to fix your tap

 

[dancinplumba]

He will be out tomorrow ASAP to fix the tap, I was just wondering for the moment.

What is a spur switch by the way? As Ideally I would like to keep my central heating on but the water off.

hi, as said leave it on, you wont have a problem

 

[AWheating]

you could isolate the cold to the boiler which will isolate all hot taps and then turn your cold mains back on so you have water.

 

[jase158]

Turn it on, take the chance, have your heat excahnger changed for £200-300 in 6 months
leave it off, dont take the chance, save £200-£300.

I know which one I would do.

 

[dancinplumba]

Turn it on, take the chance, have your heat excahnger changed for £200-300 in 6 months
leave it off, dont take the chance, save £200-£300.

I know which one I would do.

could you please explain ?

 

[lame plumber]

dancin is gettingPMT again:tongue:

 

[dancinplumba]

dancin is gettingpmt again:tongue:

yes !!!

 

[glenno1]

Im with dancin on this,boiler will be no problem

 

[lame plumber]

As far as I know it is a Ferroli Combi F30 D (I think). With a dual heat exchange for hot water and then for central heating.

If its the ferroli Im thinking of then the ch and dhw pipework run through the same heat exchanger, such that if you turn off the cold feed to the boiler, the hw side will run dry or part dry, so there is a risk of the remnants in the hex to boil away and even pressurise up as stem if things go wrong. In this situation you should leave the hot in let and oulets open to avoid hex problems, being thats going to be a pain in the bum, just dont use the boiler till the taps repaired, simples and cheapest option. Saves you getting a popping and hissing noise from the boiler

 

[dancinplumba]

If its the ferroli Im thinking of then the ch and dhw pipework run through the same heat exchanger, such that if you turn off the cold feed to the boiler, the hw side will run dry or part dry, so there is a risk of the remnants in the hex to boil away and even pressurise up as stem if things go wrong. In this situation you should leave the hot in let and oulets open to avoid hex problems, being thats going to be a pain in the bum, just dont use the boiler till the taps repaired, simples and cheapest option. Saves you getting a popping and hissing noise from the boiler

that model is the modena he

 

[lame plumber]

I came across a much older model that wasnt condensing with dual hex fm memory, didnt study it in detail as it was going in the scrap pile, anyway dancin hop it and go back to your hot water bottle and pmt, nicking my one good thought of the evening:46:

 

[Nostrum]

If it boiled the domestic hot water then it would boil the heating water as well, the boiler won't fire on H/W demand and the heating water circulating will be enough to dissipate the heat providing it is working correctly that is (debatable I suppose being a ferroli)

 

[lame plumber]

If it boiled the domestic hot water then it would boil the heating water as well, the boiler won't fire on H/W demand and the heating water circulating will be enough to dissipate the heat providing it is working correctly that is (debatable I suppose being a ferroli)

not if the runs thro the hex are separate supplies.

 

[dancinplumba]

I came across a much older model that wasnt condensing with dual hex fm memory, didnt study it in detail as it was going in the scrap pile, anyway dancin hop it and go back to your hot water bottle and pmt, nicking my one good thought of the evening:46:

think you are the one thats hoppin lol not me

 

[dancinplumba]

its not f30 D its B and has early dualpass heatex like wb junior

 

[dancinplumba]

not if the runs thro the hex are separate supplies.

obviously they will be separate supplies......DOH

 

[lame plumber]

obviously they will be separate supplies......DOH

da da da da da da, were just hoppin along on the crest of a wave......:iamwithstupid:

 

[Nostrum]

obviously they will be separate supplies......DOH

You'd be hopping so anyway