No hot water on gravity system

[bella100]

Hi all been at an ongoing job standard gravity system heating is fine cylinder flow piping hot cylinder return no to little heat tried venting and it works after a hassle of cracking nuts and vents then after about 3 days it blocks again how often do the coils become sludged up is it quite common also could the pump be pulling in through the vent ? Cheers guys and girls

 

[Last Plumber]

You'd be best off getting a Heating Engineer to sort it for you. There are a few things that it could be to be honest.

 

[bella100]

Hi thanks like what are you thinking pumps fine zv operating as normal can't think what else it could be cheers other than air or blockage stat calls for hot water fine

 

[zzzjim]

On just gravity they can be temperamental with starting just hot water ,
(esp if set high and start to kettle )
In cold weather ch load is robbing tank of any extra !
I remember listening for creaking of pipes up to cylinder ,was a clue it was flowing on just HW . ( a quick flick to Ch pump and back again if it failed ) ... Antiques require patience .

 

[Last Plumber]

Hi all been at an ongoing job standard gravity system heating is fine cylinder flow piping hot cylinder return no to little heat tried venting and it works after a hassle of cracking nuts and vents then after about 3 days it blocks again how often do the coils become sludged up is it quite common also could the pump be pulling in through the vent ? Cheers guys and girls

Sorry, I have just re read your post. You are a plumber are you ?

 

[bella100]

Haha sort of more of an electrician maybe I shouldn't of said that on here

 

[Last Plumber]

Haha sort of more of an electrician maybe I shouldn't of said that on here

Have you tried draining and disconnecting the coil to check it is clear?
Does water flow through it ok?
There's no Gate valve on return from cylinder that is stuck or blocked?
No overflows running?

 

[Last Plumber]

Haha sort of more of an electrician maybe I shouldn't of said that on here

Have you tried draining and disconnecting the coil to check it is clear?
Does water flow through it ok?
There's no Gate valve on return from cylinder that is stuck or blocked?
No overflows running?

 

[bella100]

Thanks for your help buddy, was going to try and investigate the coil in the morning they did say that the overflow would occasionally run but it's never done it while I've been there if it is going up the vent could you cap off the vent to force it round only temporarily of course until it clears

 

[Last Plumber]

Thanks for your help buddy, was going to try and investigate the coil in the morning they did say that the overflow would occasionally run but it's never done it while I've been there if it is going up the vent could you cap off the vent to force it round only temporarily of course until it clears

NO TOO DANGEROUS !
Don't do that.

 

[Last Plumber]

Did it start all of a sudden or has it been a gradual decline

 

[bella100]

Hi not to sure as the people in the house are completely useless I get it going and a week 2 weeks later I get a call saying no hot water again

 

[Last Plumber]

You need to look at the things I mentioned plus check if air being sucked into vent.
Colour of water should give a clue, If its rust coloured your getting air introduced regularly ( normally)

Have a look at the tanks in loft and vent first.

 

[Last Plumber]

You need to look at the things I mentioned plus check if air being sucked into vent.
Colour of water should give a clue, If its rust coloured your getting air introduced regularly ( normally)

Have a look at the tanks in loft and vent first.

 

[bella100]

If it is drawing air through the vent how can that be stopped would slowing the pump help?

 

[Last Plumber]

If it is drawing air through the vent how can that be stopped would slowing the pump help?

If it is and the problem hasn't always been there then it could be a partial blockage I suppose. It's difficult to say. You can only use a process of elimination. Look at the obvious first. The pump shouldn't really effect the DHW if it's a gravity system so if it is it needs Sorting.

Once you've been back, if you're still stuck, Post us some pics ?

Pipe layout around cylinder, boiler, tanks etc.

Try and weigh up where cold feed from tank goes in if it's indirect. It could be primatic.

Have you checked which system it is ?

 

[Last Plumber]

If it is drawing air through the vent how can that be stopped would slowing the pump help?

If it is and the problem hasn't always been there then it could be a partial blockage I suppose. It's difficult to say. You can only use a process of elimination. Look at the obvious first. The pump shouldn't really effect the DHW if it's a gravity system so if it is it needs Sorting.

Once you've been back, if you're still stuck, Post us some pics ?

Pipe layout around cylinder, boiler, tanks etc.

Try and weigh up where cold feed from tank goes in if it's indirect. It could be primatic.

Have you checked which system it is ?

 

[bella100]

What is a primatic? When I split the nut on the top of the coil it was pretty black and funky

 

[bella100]

Cheers for your help really appreciated nice to have someone knowledgable to guide us numptys through

 

[Last Plumber]

If it has a vent off the coil it will be indirect so if you've seen one there don't worry about it.

FYI It's a single fed cylinder ( heating filled via annular inside ). Normally one tank in loft ( no small 10 gal FE tank present )

 

[bella100]

Oh no it's not that system well thanks again I'll update tomorrow with pics cheers

 

[Last Plumber]

Oh no it's not that system well thanks again I'll update tomorrow with pics cheers

Good Luck. Remember, Patience is a virtue !
By the sound of it, yours will be tried tomorrow.

 

[Last Plumber]

Oh no it's not that system well thanks again I'll update tomorrow with pics cheers

Good Luck. Remember, Patience is a virtue !
By the sound of it, yours will be tried tomorrow.