Immersion/Hot Water Problem

the_viper2kie

Hi Folks,

Have a small problem with the hot water system in my newish house. For the last few weeks we've noticed that on random mornings there is no hot water available for the shower despite having the same heating times each day and pretty consistent usage. One day perfectly hot, next day not so warm.
Have a gas boiler feeding 3 circuits, 2 x radiator circuits and 1 x hot water to tank in hot press on top floor.
For the last few times the hot water has been turned on I've checked the hot water pipes into the cylinder and sometimes they are hot/sometimes cold.
I also notice that on the thermostat on the hot water tank that when I turn the dial up and down I don't hear a click like I used to and like I would hear on standard room thermostat...so I thought it might be the thermostat that is gone.
My other theory is that it could be the automatic valve on the hot water circuit, I have switched pushed the lever on this to manual which I thought should open it and send water to the cylinder but doesn't seem to be doing that.

Anyone got any thoughts on this?

Thanks,
H

Micky Dolenz

When the heating is off, move the arm off the hot water valve over. you should feel resistance and it will spring closed. when it's on you should feel no resistance on the arm as it is open. You can also use this method to check if the cylinder stat is working when heating is on by turning stat up and down.

When you pull the arm over do you lock it into the groove to keep it open?

Go to your cylinder, you should see two pipes that enter the cylinder parallel and about 18" apart, on the bottom one there may be a wheel handled valve, it may be half open. Check to see if it isn't nearly closed.

the_viper2kie

Thanks Micky,

I did the test like you described, with heating off I feel a resistance, when turned it on at control panel it moved freely, I left it locked in the up position. Now this time I only turned on the hot water and sure enough water is going to the tank now no problem...all this afternoon it wasn't! The only difference is that the other zones were also opened today. Is it possible that the system is not balanced correctly and hot water is going preferentially to the other zones/rads instead?
Also on the thermostat on the cylinder, should you not hear a click when you turn the dial to a setpoint higher than the internal temp in the tank? I don't hear this anymore and I am sure I used to.

Thanks again,

H

Micky Dolenz

some stats click, some don't. test it as you did before. Put lever arm into auto position, (as in take it off the groove). Turn on hot water. Turn stat down, resistance on arm would say it's off. turn it up and resistance should be gone.

Did you check the other valve I spoke off?

the_viper2kie

Yeah, checked that other valve and a good 2 and a half turns to closed position. Just tried that test there with on the stat. With the stat turned fully down (20oC) the slider on the valve moves freely. What do you think this means?

Micky Dolenz

the_viper2kie wrote: »

Yeah, checked that other valve and a good 2 and a half turns to closed position. Just tried that test there with on the stat. With the stat turned fully down (20oC) the slider on the valve moves freely. What do you think this means?

Is the water temp below that?

The stat may be faulty, but if it is, it has failed with connectors open. If that is the case you should be getting hot water whenever hot water option is on.

the_viper2kie

Micky Dolenz wrote: »

Is the water temp below that?

The stat may be faulty, but if it is, it has failed with connectors open. If that is the case you should be getting hot water whenever hot water option is on.

I reckon the water is above that but I will leave it on now for an hour and check it again. I remember moving the valve to manual earlier today and moved freely however no hot water was going to the tank so a bit confused...thats why I wondered about balancing as other zones were open at the same time. It's a split level house so the tank is approx 1.5 floors higher than the valves if that would make a difference.

H.

Micky Dolenz

Maybe. Is it a sealed system? Whats your pressure gauge reading?

the_viper2kie

Micky Dolenz wrote: »

Maybe. Is it a sealed system? Whats your pressure gauge reading?

Pressure is at 1.2 bar currently, what should it be at?

Micky Dolenz

the_viper2kie wrote: »

Pressure is at 1.2 bar currently, what should it be at?

Thats ok.

Does it work ok with all zones on now?

kccfc

micky my pressure is at 3.5bar, is this dangerously high,how do i drop it??

Micky Dolenz

kccfc wrote: »

micky my pressure is at 3.5bar, is this dangerously high,how do i drop it??

High all right.

Get a bucket, open a vent on a rad and fill the bucket.It'll be slow but the handiest way to do it. Don't take the vent out as it can be tricky to get them back in.

the_viper2kie

I've turned on all zones now and hot water is going to the rads. The pipes are still hot to the immersion tank but not sure if this is just holdup. Will wait and see if it cools over time.

the_viper2kie

Thanks Micky for all your help. I have a bit of an update...been trying a few things over the past few days. Now when the heating starts up and all three zones are on...water goes to the rads upstairs and downstairs with nothing to the hot water tank. When I turn off the upstairs rads heating, hot water goes to the tank. When I have all three zones on and I turn off the downstairs rads, hot water goes to the tank. So it appears that it can't send hot water to all three zones at the one time.
Does this mean the system isn't balanced correctly? Or what else could cause this?

Micky Dolenz

Certainly sounds like a circulation problem all right. Since it's a new development I would be thinking there may be a problem with your pump or there is a slight blockage in the system somewhere. enough to slow down/stop circulation when pump is running on full system but not enough when pump is on one zone.

You could fit a pump especially for the primary circuit, ( hot water circuit) but you would be treating a symptom and the not the cause. Providing it worked right before.

the_viper2kie

Micky Dolenz wrote: »

Certainly sounds like a circulation problem all right. Since it's a new development I would be thinking there may be a problem with your pump or there is a slight blockage in the system somewhere. enough to slow down/stop circulation when pump is running on full system but not enough when pump is on one zone.

You could fit a pump especially for the primary circuit, ( hot water circuit) but you would be treating a symptom and the not the cause. Providing it worked right before.

Thanks Micky, How easy is it to diagnose a blockage in the system and more importantly to rectify it?
Why would it be going preferentially to the rad zones compared to hot water tank? Would there be a greater pressure drop on the rad circuits? The radiators on the upstairs curcuit are the exact same height as the hot water tank and they heat fine with all three zones on,

Micky Dolenz

the_viper2kie wrote: »

Thanks Micky, How easy is it to diagnose a blockage in the system and more importantly to rectify it?
Why would it be going preferentially to the rad zones compared to hot water tank? Would there be a greater pressure drop on the rad circuits? The radiators on the upstairs curcuit are the exact same height as the hot water tank and they heat fine with all three zones on,

Sorry, I thought your cylinder was higher then the rest of the system.

Remove the motorised head off the valve body for the primary circuit. Move the spindle, ensure it moves freely. It may be sticking.

the_viper2kie

Micky Dolenz wrote: »

Sorry, I thought your cylinder was higher then the rest of the system.

Remove the motorised head off the valve body for the primary circuit. Move the spindle, ensure it moves freely. It may be sticking.

Ok thanks, I'll give that a go tomorrow. Is that an easy thing to do? The valves are like these ones on http://www.ephcontrols.com/. If these were sticking how would the water flow in this circuit when I just turn off/close a valve on one of the other circuits without cycling the hot water circuit valve at all, i.e. starting with all three zones open and just closing one of the others causes it to heat.

The other thing I was wondering about is an airlock in the system. Given that radiators are bled, do you need to bleed the primary circuit as you call it ever?

Micky Dolenz

Press detach button and pull gently.

It may not be opening fully and restricting flow. Once head is off you will see a spindle, you should be able to turn it by hand.

There should be an automatic air vent on flow at cylinder. It'll be a brass bottle type fitting maybe have a small black cap. see if the black cap is loose.

andy2die4

Micky Dolenz wrote: »

Did you check the other valve I spoke off?

If this valve was left 1/4 open, it would push more water around the system and still give you hot water