Problem with insufficient hot water

[spiceyokooko]

This has been an ongoing problem for some time and I've finally decided to get round to fixing it and would appreciate some help and advice.

The boiler is a Potterton Flamingo 50s, the hot water tank is an indirect cylinder and the 2 port valve is a Honeywell V4043.

The central heating works fine - the radiators heat up no problem. The problem is, I can't seem to get hot water in much quantity from the system.

With hot water only on, I get luke warm water. I have to switch the central heating on to get any hot water from the system and even then there's very little of it - just enough to have a bath in 6 inches of hot water before it goes luke warm and that's after having the central heating on for 3-4 hours. With the price of gas going up, I obviously don't want to have to keep turning the central heating on just to get a little hot water from the system.

My first thoughts were that it was the Honeywell 2 port valve that was causing the problem, but I'm wondering if the hot water cylinder needs a new thermostat?

Any thoughts?

Any help appreciated, thank you.

 

[Terry lambert]

Is the stat making good contact with the surface of the cylinder? Secured with a strap

The stat should be about a third up from the bottom of the cylinder

What temp is the stat set to, should be 60 - 65 normally

Is it a short circuit from the boiler to the cylinder and have you got the boiler stat turned down?

Does both the flow and return pipe on your cylinder get hot when your calling for hot water?

You could link out the cylinder stat to rule that out

 

[Terry lambert]

Have you got an air vent by the cylinder you could bleed to check for air?

Have you got a balancing or gate valve on the cylinder return that is either shut down too much or closed

Does the two port open and close when you turn the stat up and down?

 

[CannyBuyer]

Have you got an air vent by the cylinder you could bleed to check for air?

Have you got a balancing or gate valve on the cylinder return that is either shut down too much or closed

Does the two port open and close when you turn the stat up and down?

If you are confident and careful around electricity you can check of if the boiler thermostat comes on by just moving the tension wire away from the thermostat block and moving the thermostat block away from the HW cylinder. The motorised valve should move to open if the programmer board is set to hot water on.

You can check the connections to the thermostat by removing the plastic cover of the and shorting the two connections inside with insulated multi meter leads (only 45V on these wires in my case) while an assistant watches the movement of the motorised valve. (do not do any of the above if you are not confident)

To be really safe turn the whole CH power supply off between tests; there has to be a master switch somewhere find it and use it.

 

[spiceyokooko]

Is the stat making good contact with the surface of the cylinder? Secured with a strap

Hi Terry, thanks for your comments, I'll try and answer them as best I can.

The thermostat is as you say a third the way up the cylinder. It's a little rectangular box with a turn knob on the top for adjusting the temperature. The Temperature is set to 90. It's not secured by a strap. There's two black wires coming out of the bottom, one goes to the Honeywell 2 port valve and 1 goes to the timer box. I can take the front of the little box off and there's the wires inside I can access.

The stat should be about a third up from the bottom of the cylinder

Yes that's where it's positioned.

What temp is the stat set to, should be 60 - 65 normally

It's currently set at about 90.

Is it a short circuit from the boiler to the cylinder and have you got the boiler stat turned down?

I'm not sure what you mean by 'short circuit' but yes the cylinder is right next to the boiler. The boiler control knob is set to maximum.

Does both the flow and return pipe on your cylinder get hot when your calling for hot water?

I'll check on that as soon as the heating fires up and I'll get back to you.

You could link out the cylinder stat to rule that out

Yes, that's a good idea, I could try that

Many thanks for your help.

 

[spiceyokooko]

Have you got an air vent by the cylinder you could bleed to check for air?

There's a drain tap at the bottom of the cylinder, not sure if there's an air vent, although the boiler is vented to the outside wall.

Have you got a balancing or gate valve on the cylinder return that is either shut down too much or closed

Not sure what this is, but there don't appear to be any valves on any pipework coming out of the cylinder.

Does the two port open and close when you turn the stat up and down?

Good question, I don't think so, presumably the system needs to be on and running for me to try this? or should it click when it's off as well?

I can check on this if I turn on the system.

If it's any help, the house was built in the early 80's and nothing's been changed or updated since then. So the system is probably about 30 years old.

I can take some pictures of the system if this would help?

 

[spiceyokooko]

I've switched the hot water and central heating on and off a couple of times and the 2 port valve does nothing.

I've twiddled with the cylinder thermostat as well and that does nothing as well!

 

[Terry lambert]

What I mean by a short circuit is the cylinder close to the boiler, if the boiler stat was turned down you would not get much heat to the cylinder with the boiler cycling on and off

A couple of pictures may help

Make sure the clock is calling for heat and then turn the stat up and then down to make sure the valve is motoring.

Where the flow and return enter the cylinder it is good practice to have a bleed valve on the higher connection, bleed this.

Do the two pipes get hot when calling for hot water?

 

[Terry lambert]

Is the clock demanding hot water?

 

[spiceyokooko]

Here's some pictures of the system if it helps.

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• spiceyokooko
• 7 Dec 2012
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• spiceyokooko
• 7 Dec 2012
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• spiceyokooko
• 7 Dec 2012
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[spiceyokooko]

Is the clock demanding hot water?

I'm sorry, could you explain this?
Clock? The timer? On which system, hot water or central heating?

I'm pretty handy with lots of things - cars, computers, most DIY etc plumbing I'm afraid is a mystery!

 

[spiceyokooko]

What I mean by a short circuit is the cylinder close to the boiler

As you can see from the pictures, the cylinder is pretty close to the boiler.

Make sure the clock is calling for heat and then turn the stat up and then down to make sure the valve is motoring.

I've tried turning the thermostat switch whilst the system is one and the 2 port valve does nothing.

Where the flow and return enter the cylinder it is good practice to have a bleed valve on the higher connection, bleed this.

There's a bleed pipe on the bottom of the cylinder (you can just see it on the left hand side of the orange cylinder in one of the pictures).

What I mean by a short circuit is the cylinder close to the boiler

As you can see from the pictures, the cylinder is pretty close to the boiler.

Do the two pipes get hot when calling for hot water?

I'll check this by switching the system on to hot water only and see what happens, presumably the 2 port valve needs to be in auto position?

 

[Terry lambert]

I think itvmight be best to call an engineer to carry out some electrical tests

 

[spiceyokooko]

Okay Terry, thanks for your help.

 

[Terry lambert]

No worries