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Discussion Starter · #1 ·
Im getting a "F" offed with my central heating, and, at the moment is now only providing centeral heating, no hot water,
My problems started last week, tepid hot water and not very good heating, I changed the Pump for a new Grundfoss pump, as every now and then the boiler woud trip if the boiler stat was set to max, + the pump was getting noisy, Now this changed nothing, so, moving on to the next thing, change the 3 port valve, especially as I could not put the valve into mid position, this appears to have made no difference, even in the override position, still no hot water!!!
so I have now dismantled the airing cupboard to get to the tank, the pipe feeding the coil is NOT getting hot, BUT what I have found is a strange looking valve on the bottom of the coil, looks to me to be either a non return or water temp valve, I dont ever recall seeing one of these on a tank before, if it is some sort of vale, can they jam??
HELP
 

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Ian is this valve a manual valve or moterized ? If it is motorised is it a 3 port or 2 ? I will be able to tell you more once youestablish what you have
 

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Discussion Starter · #4 · (Edited)
3 port motorised, rightly or wrongly, i have assumed if you leave the valve in the mid position you should get both Hot water, and heating, but the there is no hot, Im assuming by doing this I should over ride the hot water stat thats strapped on the side of the tank
 

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Turn your room stat right down. Turn your tank stat right up.
Dose the stat clic? if not it may be Shagged, and not calling for heat.

"so I have now dismantled the airing cupboard to get to the tank, the pipe feeding the coil is NOT getting hot, BUT what I have found is a strange looking valve on the bottom of the coil, looks to me to be either a non return or water temp valve, I dont ever recall seeing one of these on a tank before, if it is some sort of vale, can they jam??"

Was the system fully vented after changing the pump/3port?
 

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if the is a Honewel type valve there should be a metal lever that you can slide over and park it in an open position this should then allow flow through the water coil try that
 

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Like eastern has said it could well be the tank stat at fault because on a 3 port vavle the tank stat has a 3 core connection with a common and a normaly open contact and a normaly closed which is needed to allow current to flow through the normaly open cantact when the tank stat is satisfied in order for the heating to still call for heat if required
 

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Discussion Starter · #8 ·
Like eastern has said it could well be the tank stat at fault because on a 3 port vavle the tank stat has a 3 core connection with a common and a normaly open contact and a normaly closed which is needed to allow current to flow through the normaly open cantact when the tank stat is satisfied in order for the heating to still call for heat if required
if you have the valve in the "both open" Dosent the hot water coil get hot as it is being shared, if it is the tank stat, is there any way to over ride it to prove its at falt, It should be a easy thing to check as its only a Bi Metallic strip and a Micro switch, assuming its feed, load and earth??
 

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You can test it with a multi meter if you have one not sure what you mean when you stat feed,load and earth ? On a honeywell stat if this is what you have there are no earth or neutral connection there is just live in Common and live out on either the N/O or N/C contacts depending on what the stat is doing ( calling for heat or satisfied)
 

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heating

have you had any luck sorting this out? pm me if you haven't and I can give you my number and we can try and sort something out,cheers paul:tup:
 

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strange valve off the return from the cylinder does it have pipe coming out slightly lower sort of stepped with like a conical cap on it think we used to call em a cytrol valve have known em to get shitted up and even pack up if so i wouldnt see a point in having one in a modern system.
 

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Discussion Starter · #12 ·
Here is another question,
If my motorised 3 port valve is in the mid position, [manual] so both ports are open, as far as I can understand, the boiler is running , and the rads are hot, Why is the domestec not getting hot, as long as the boiler/pump is running and the feed is open the loop should get hot??,
Im still curious about this valve thing on the bottom of the tank coil, it certainly looks like some sort of valve water comes in from the side as it has a blue plastic cap over what looks like a spindle? can it be either a overheat thermostic valve or pressure control valve?
 

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Discussion Starter · #13 ·
strange valve off the return from the cylinder does it have pipe coming out slightly lower sort of stepped with like a conical cap on it think we used to call em a cytrol valve have known em to get shitted up and even pack up if so i wouldnt see a point in having one in a modern system.
This sounds promising, whats it for? I was just about to drain the system down again and have a look at this, possibly with the intent of stripping out the insides so I can get some HW back,
The valve has a blue cap not not unlike a rad knob, and what looks like a stop cast into the body so it cant be rotated past a certain point,,
My system is quite old, and the tank has to be at least 20 years old so Im hoping it all comes undone without busting open the tank:shock::shock:
 

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This sounds promising, whats it for? I was just about to drain the system down again and have a look at this, possibly with the intent of stripping out the insides so I can get some HW back,
The valve has a blue cap not not unlike a rad knob, and what looks like a stop cast into the body so it cant be rotated past a certain point,,
My system is quite old, and the tank has to be at least 20 years old so Im hoping it all comes undone without busting open the tank:shock::shock:
post a pic of the valve m8.

usually on the return from the cylinder (the bottom pipe) you would fit a gate valve so you can slow down the flow through the coil in the cylinder allowing the water in the cylinder to draw maximum heat from it.

sounds like your valve is the problem as it preventing the dhw circuit circulating
 

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One of the most common problems i find is the motor burnt out in the 3 port valve or the valve siezed by limescale so its not actually moving. Remove the head off the valve (no water is involved) to leave just the flat edge of the valve protruding and turn this with a pair of pliers to the desired position. Then try the boiler again
 

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Discussion Starter · #16 ·
One of the most common problems i find is the motor burnt out in the 3 port valve or the valve siezed by limescale so its not actually moving. Remove the head off the valve (no water is involved) to leave just the flat edge of the valve protruding and turn this with a pair of pliers to the desired position. Then try the boiler again
No, Its a brand new valve and in a fixed mid position, so that elliminated:tup:
 

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Discussion Starter · #17 ·
Removed the valve from the bottom the cylinder, its a Drayton temp control valve, not in the best condition as I managed to break the internal spildle with my fingers, somehow, I dont think its the problem as it was open when removed, unless the the faffing about to remove the valve has released the valve from a shut position??? but it was a bit gummy inside,
Now for the next question??
Assuming I get the system all back together, do I need to bleed the coil, I think it bleeds to the overflow in the loft
 

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Hi v8ian,

Unfortunately it will depend on the run of pipes, as to whether there is a gradual climb up to the header tank or not. In practise unless you have a section of pipe which will give you a large airlock, normally the pump will move the water along fast enough to carry air bubbles along that will then self vent into the header tank. I am assuming open vented system here.

If you have any bleed screws in your system as long as they will undo easily enough it is always a good idea to crack them off to vent off any air that may be trapped.

Cheers.

Russ.
 

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Check if the expansion tank in loft is empty. Then check for blocked cold feed.

Rog.
 
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