Unvented Cylinder No Hot Water

[Yogiblair]

Hi,

I have a Tribune Range HE, direct unvented cylinder with a gas boiler. Recently I had a very small leak (more of a weap) from the two port valve on the CH. I isolated the water supply, electricity and closed off the valves I could see directly effecting this circuit. I removed the actuator assembly cleaned up the two port valve, re-seated everything and all appeared ok. The leak has been fixed.

The next day after showers I ran out of hot water. One thing to note that I have been running this as an indirect system for over a year (immersion heater switched off) and always had sufficient levels of hot water.

The CH works fine. In investigating I noticed that i had zero pressure at the expansion tank. (when removing the two port valve there was a very small release of pressure) I opened the fill loop and now have 1.3bar at the expansion tank.

I can get hot water by turning on the immersion heater, however I have tried several tests now with the immersion heater off and after using the contents of the tank I get cold running through.

I have read that my problem may be with the motorized valve on the primary flow line. I have tried running this in manual but still get no hot water unless the immersion heater is on.

Any help greatly appreciated.

 

[Simon F]

so the lack of hot water has only occurred after the work you did yes?
apart from the possibility of a completely unrelated fault also occurring at the same time,
the issue more probably is that something has been changed, not put back properly.
Have another look, what did you change? has something been missed?
start simple - have the valves that were closed been opened?
did you change the wiring? is it wrong?

 

[Gray0689]

How do you know if the motorised valve you possibly fixed is working correctly

Open it manually and turn heating on see if you get hot water then

 

[Yogiblair]

Simon Thanks for the reply. Yes this has only happened since i removed the CH two port valve actuator and re-seated it. I closed two valves and opened them again at this time. I am thinking it is related to the small amount of pressure that escaped when I removed the CH two port valve and that there should have been another valve in this circuit closed? As I said I had zero pressure at the expansion tank but opening and closing the fill loop then gave me 1.3bar.

 

[Yogiblair]

How do you know if the motorised valve you possibly fixed is working correctly

Open it manually and turn heating on see if you get hot water then

The motorized valve on the central heating doesn't have a manual option (only the valve on the primary flow line). it is working because it turns when the central heating kicks in

 

[Simon F]

How do you know if the motorised valve you possibly fixed is working correctly
Open it manually and turn heating on see if you get hot water then

The CH works fine.
I have read that my problem may be with the motorized valve on the primary flow line. I have tried running this in manual but still get no hot water unless the immersion heater is on.

what Gray is saying is turn the central heating on, the boiler is then working Yes?
(so the pressure you mentioned is not an issue.)
then manually open the small metal lever on the 2 port valve to the hot water cylinder,the lever has a position that it can be held in so that it remains open, if the hot water is then getting hot - you still have an issue with the 2 port valve.

 

[Yogiblair]

what Gray is saying is turn the central heating on, the boiler is then working Yes?
(so the pressure you mentioned is not an issue.)
then manually open the small metal lever on the 2 port valve to the hot water cylinder,the lever has a position that it can be held in so that it remains open, if the hot water is then getting hot - you still have an issue with the 2 port valve.

I have done this with the metal lever in the manual position and the central heating on. Left it for several hours with the immersion heater off (power switch off) and still no hot water.

 

[Simon F]

I will come back then to the first answer, that if the problem only happened AFTER you did the work on the two port valve something must be closed somewhere to be preventing any flow.
is the valve put back together properly?
might be time to call a plumber to resolve the problem, as ability through a keyboard has limitations.

 

[Yogiblair]

I will come back then to the first answer, that if the problem only happened AFTER you did the work on the two port valve something must be closed somewhere to be preventing any flow.
is the valve put back together properly?
might be time to call a plumber to resolve the problem, as ability through a keyboard has limitations.

I will check valves again, but as I said I only closed two and then opened two. the two port valve is such a simple piece that I do not believe it be possible to not put it back on correctly. Thanks for your suggestions.

I am thinking that I have been unlucky and my problem is un-related. Perhaps it didn't like it when I powered down the system to to work on it originally. I have read elsewhere about a microswitch in the flow line two port valve and if this is faulty then even though the valve is manually open then the heating will not kick in to heat the water (although i would have thought it would still heat when the central heating is on)

 

[Howsie]

Are you sure it's back on its spindle correctly?

 

[Yogiblair]

Are you sure it's back on its spindle correctly?

I am, the two port valve I removed was on the central heating side and that works perfectly.

 

[Simon F]

ok, assumption was the valve was the one to the hot water.

is there a bleed screw somewhere that has not been opened, and the pipe is full of air?
some photos might prove helpful.

 

[Yogiblair]

ok, assumption was the valve was the one to the hot water.

is there a bleed screw somewhere that has not been opened, and the pipe is full of air?
some photos might prove helpful.

That sounds feasible. Will have a look when I get home tonight and get a couple of images. Thanks

 

[lame plumber]

could have sheared a gate valve on closing it and not noticed

 

[Whyme]

That sounds feasible. Will have a look when I get home tonight and get a couple of images. Thanks

Try and upload some photos and show us what was turned off etc. we like photos.

 

[Yogiblair]

Try and upload some photos and show us what was turned off etc. we like photos.

photo attached

1 two port valve I originally removed (CH)
2 valve i closed before removal of the two port valve
3 valve i closed before removal of two port valve
4 two port valve for hot water
5 bleed pressure from here

Ok something I have noticed tonight but was sure wasnt the case before. The boiler is not firing when hot water program is on. only fires for CH

 

[Whyme]

You havent dislodged a wire fron the hw 2 port when wiring new ch one back in have you.? or did you just swap the body. Id double check valve 3 if i were you.

 

[Yogiblair]

You havent dislodged a wire fron the hw 2 port when wiring new ch one back in have you.? or did you just swap the body.

The old one went back on after i cleaned up the gunk from the leak. the wires are on the red plug to the left of the picture. i am convinced that this two port valve is working and that it is for the CH.

 

[Whyme]

double check valve 3.

 

[Gray0689]

Why did you bleed pressure from temp pressure relief valve
That's the domestic water not heating

 

[Yogiblair]

Make sure valve 3 is fully open.

valve 3 is open. heat is on the pipe either side of the valve

 

[CM25]

Cyl stat turned down?

 

[Yogiblair]

Why did you bleed pressure from temp pressure relief valve
That's the domestic water not heating

my problem is with the water, not heating. I bleed pressure from this tonight following early suggestion on here. It did release air before water in to the tundish

 

[Whyme]

valve 3 is open. heat is on the pipe either side of the valve

If its not after the 2 port and its calling for hw then its the hw 2port, push it over manually to see if you get flow with the pump running. what grey meant was the water coming out of that valve when turned is the same water you get at the hot taps not 'boiler' water.

 

[Yogiblair]

If its not after the 2 port and its calling for hw then its the hw 2port, push it over manually to see if you get flow with the pump running. what grey meant was the water coming out of that valve when turned is the same water you get at the hot taps not 'boiler' water.

With no 8 in manual i have got heat on pipe at 6 but cool on 7. 8 is also very warm.

 

[Yogiblair]

Cyl stat turned down?

set to 60 degrees

 

[Whyme]

By 7 is that the other side of the 2port or the pipe next to it.

 

[Yogiblair]

By 7 is that the other side of the 2port or the pipe next to it.

just above 7 to the left is the primary coil in (or out?) the pipe to the right is cold water

 

[Gray0689]

Take off the motorised valve head and turn open manually and see if any heat will pass then
I'm still thinking its a faulty zone valve

 

[Whyme]

The red cap above the no. 6 have you tried bleeding that to see if its just air.

 

[Yogiblair]

Take off the motorised valve head and turn open manually and see if any heat will pass then
I'm still thinking its a faulty zone valve

done this and the valve is already in the open position but closed and opened it again to be sure. the pipe above is hot and below cold

 

[CM25]

High limit stat tripped under black cap on cyl stat?

 

[Yogiblair]

The red cap above the no. 6 have you tried bleeding that to see if its just air.

how would i do that? the plastic cap just screws off. there is a small pink washer on it

 

[Yogiblair]

High limit stat tripped under black cap on cyl stat?

ive tried unscrewing this and pushing the button a few times. its not made any difference?

 

[Simon F]

Why did you bleed pressure from temp pressure relief valve
That's the domestic water not heating

my problem is with the water, not heating. I bleed pressure from this tonight following early suggestion on here. It did release air before water in to the tundish

if you are referring to my question, (which was before any pictures)

ok, assumption was the valve was the one to the hot water.
is there a bleed screw somewhere that has not been opened, and the pipe is full of air?
some photos might prove helpful.

then what I had in mind was this

The red cap above the no. 6 have you tried bleeding that to see if its just air.

I think it is really time to call a qualified professional to sort this out, it is after all an unvented cylinder!
the potential danger from things not working properly is worrying!

 

[Whyme]

:iagree:

 

[Rickster123]

I think you have done more than enough fiddling now and it's time to get a professional in to sort the problem. Unvented cylinders can be extremely dangerous if not set up correctly and I think if you carry on fiddling with random valves it will only lead to further problems for you.Put a post on the looking for a Plumber part of the forum.

 

[Yogiblair]

Whyme, can you explain how to bleed the red cap?

 

[Rickster123]

Whyme, can you explain how to bleed the red cap?

It's self bleeding. Please seek assistance from a local engineer.

 

[Yogiblair]

It's self bleeding. Please seek assistance from a local engineer.

ok guys getting the picture. why was i told to try and bleed it if its self bleeding however. I understand that a pressurized system can be dangerous. I am an engineer from another discipline and understand the fault finding process. Further more the fault occurred after i removed / re-seated a valve so that has a fair chance of being the root cause of my problem. I would not be surprised if air in the system was the cause.

 

[Whyme]

The cap when loose but not off lets air out automatically, sometimes thecaps are screwed shut sorry i didnt clarify that bit. like the guys say those cylinders can be very dangerouse if there tinkered with..ask around the forum for somebody..good luck pal.

 

[Yogiblair]

The cap when loose but not off lets air out automatically, sometimes thecaps are screwed shut sorry i didnt clarify that bit. like the guys say those cylinders can be very dangerouse if there tinkered with..ask around the forum for somebody..good luck pal.

One last thing for my understanding. I ran for over a year with the immersion power off so my hot water was being heated from the gas boiler i have no problems with hot water during the summer when my heating thermostat is turned away down, so essentially off. That says to me the the boiler must fire to heat my hot water. At the moment it is not firing for hot water, only CH.

 

[Whyme]

Yep it should do both independantly of each other or both at the same time via the programmer. youve got an 's' plan system ie two 2port valves that divert the water being circulated by the pump to whichever circuit the 2ports are open too. if ones shut that circuit doesnt get hot visaversa.

 

[Howsie]

Oh your an engineer, that's alright then. You automatically qualify to work on unvented systems a d gas boilers.

I'm out of here, still working on that bridge at the bottom of my garden.

 

[Yogiblair]

Oh your an engineer, that's alright then. You automatically qualify to work on unvented systems a d gas boilers.

I'm out of here, still working on that bridge at the bottom of my garden.

did I say I was qualified to work on an unvented system?

 

[Masood]

did I say I was qualified to work on an unvented system? i dont think so dip ****.

Nice! You've had tons of useful advice and you're abusing one of the guys that helped you.

Howsie's point is very valid. Your engineering skills are in a different arena, and whilst the fault-finding process may have some common aspects, the specific knowledge required is very different. From the way you describe your problem and the terminology you use it's obvious that you really don't know much about unvented cylinders or heating systems. That's fine, but drop the arrogance. You didn't say in as many words that you're qualified, but by fiddling, and stating that you're an engineer, the implication is very clear that you consider yourself somewhat qualified.

 

[Yogiblair]

Nice! You've had tons of useful advice and you're abusing one of the guys that helped you.

Howsie's point is very valid. Your engineering skills are in a different arena, and whilst the fault-finding process may have some common aspects, the specific knowledge required is very different. From the way you describe your problem and the terminology you use it's obvious that you really don't know much about unvented cylinders or heating systems. That's fine, but drop the arrogance. You didn't say in as many words that you're qualified, but by fiddling, and stating that you're an engineer, the implication is very clear that you consider yourself somewhat qualified.

Yes ive had tons of useful advice of which I am thankful for. I am certainly not being arrogant, that is why I am on a forum, to seek advice on a an issue I am well aware i dont know enough about. So there is certainly no implication from my part that I am qualified. Most of the contributors on here have been helpful. I dont appreciate sarcasm about building bridges. The frustrating thing for me is that when I do get this fixed I know it will be a simple solution, but thanks for your input.

 

[Howsie]

did I say I was qualified to work on an unvented system? i dont think so dip ****.

True colours.

My point is, you are performing work on a system that has a variety of safety devices attached to ensure your safety and that of your family. You have to hold a building regs certificate to install and maintain these. A little knowledge is a dangerous thing.

FYI, the bridge reference is more of a running joke for me. Use the search button and I'm sure you'll find it.

 

[Masood]

Yes ive had tons of useful advice of which I am thankful for. I am certainly not being arrogant, that is why I am on a forum, to seek advice on a an issue I am well aware i dont know enough about.

You've had 3 or 4 people, maybe more, tell you that the problem is almost certainly with the 2-port valve. To which your answer has been "I'm convinced it's not" or variations on that theme. To ignore the advice of experienced and knowledgeable people, whose input you've sought, comes across as arrogant, even if that's not your intent.

I'd concur with that advice, by the way. You say you removed the actuator head and cleaned up the valve. That sounds like it was weeping from around the spindle. The limescale buildup can cause the spindle to become stiff and hard to turn. You also say that the actuator head is very warm. That's consistent with a not-very-powerful motor struggling against a strong resistance. We may not always explain our reasoning behind our diagnoses - it becomes a sort of mental shorthand. You're probably the same in your area of expertise. I'd still say look again at that valve.

Calling someone who has tried to assist you, only for you to dismiss that help, a dip**** is inexcusable. You don't like sarcasm, other people don't like putting time and effort into helping people for free only to be pooh-poohed. Swings and roundabouts, mate.

 

[Yogiblair]

You've had 3 or 4 people, maybe more, tell you that the problem is almost certainly with the 2-port valve. To which your answer has been "I'm convinced it's not" or variations on that theme. To ignore the advice of experienced and knowledgeable people, whose input you've sought, comes across as arrogant, even if that's not your intent.

I'd concur with that advice, by the way. You say you removed the actuator head and cleaned up the valve. That sounds like it was weeping from around the spindle. The limescale buildup can cause the spindle to become stiff and hard to turn. You also say that the actuator head is very warm. That's consistent with a not-very-powerful motor struggling against a strong resistance. We may not always explain our reasoning behind our diagnoses - it becomes a sort of mental shorthand. You're probably the same in your area of expertise. I'd still say look again at that valve.

Calling someone who has tried to assist you, only for you to dismiss that help, a dip**** is inexcusable. You don't like sarcasm, other people don't like putting time and effort into helping people for free only to be pooh-poohed. Swings and roundabouts, mate.

In so many posts the information can get lost. There is no problem with the CH 2 port calve that I removed! CH is working fine. Like so many of the other topics on here, a little bit of advice is given and then it always ends with call in an expert! Precisely what myself and all the other entrants are trying to avoid!

It has either been a real coincidence that the water 2 port valve failed on the same day as me removing the CH 2 port valve or my actions have caused this? perhaps by powering off at the breaker. The water two port valve is a danfoss HPA2. Have you heard of these failing in such a way? This valve is hot. I have read elsewhere that there is a microswitch in these. If this has failed then will that be the reason why my boiler is not firing on demand?