No hot water

[ro63rto]

Hi all.
Got a problem. If I set timer (Horstmann CentaurPlus C21) to come on in the morning for both heating and hot water, I get heating but no water unless I switch on immersion heater.

Been suggested to check motorised diverter valve but can't find it. Not near boiler (Ideal E Type) in garage and not near immersion heater in bathroom.

Can a system exist without this valve?

This is the immersion heater.

I'm stumped and don't like to give up.
Expansion tank in loft is full.
Any ideas?

Thanks in advance.

 

[Armo74]

The older systems sometimes had gate valves to isolate each circuit but if yours worked before you probably need to look harder for the valve usually next to your hot water cylinder.

 

[1983]

your boiler could be gravity hot water.
see if there are two large pipes rising up from boiler towards hot water tank position. If this is the case air cand gather in these pipes stopping circulation ar the header tank in attic could be dry or have a blocked cold feed.
If its gravity there will not be a motorised valve to control flow to hot water tank. could do with more details.

 

[ro63rto]

The older systems sometimes had gate valves to isolate each circuit but if yours worked before you probably need to look harder for the valve usually next to your hot water cylinder.

Worked fine before.

Had the hot water cylinder naked the other day. Bought new jacket so all pipes were visible all around.
Hoovered and fitted new jacket.
Followed pipes, no sign of one.

 

[ro63rto]

your boiler could be gravity hot water.
see if there are two large pipes rising up from boiler towards hot water tank position. If this is the case air cand gather in these pipes stopping circulation ar the header tank in attic could be dry or have a blocked cold feed.
If its gravity there will not be a motorised valve to control flow to hot water tank. could do with more details.

Hi, yeah, there are two going up through the ceiling and then roof of garage, into the house.

In loft I did check expansion/header tank (small version of cold tank). Its full and when I slightly press down on float, it starts to fill.

 

[ro63rto]

Oh, one thing.

Brother told me that unless the immersion heater is turned off, even though it's set to 60° (turned down now) you can hear the water boil like a kettle.

 

[1983]

does sound like gravity.
If it is there will be a pump likely next to boiler and usually 4 pipes connected to the boiler itself, 2 for heating and 2 for hot water.
The boiler is firing so electrical side ok. If the tank is full then likely blocked cold feed or air in the system. are the upstairs radiators heating to the top?

 

[ro63rto]

does sound like gravity.
If it is there will be a pump likely next to boiler and usually 4 pipes connected to the boiler itself, 2 for heating and 2 for hot water.
The boiler is firing so electrical side ok. If the tank is full then likely blocked cold feed or air in the system. are the upstairs radiators heating to the top?

Seem to remember 6 pipes, one of which has the 3 speed pump.
All rads heat fully. Bled them first day we turned on heating a few weeks back.

 

[ro63rto]

UPDATE:

I went into garage next to boiler and using walkie talkies, got my brother to switch on timer and select HW. Boiler did not fire up.
I then got him to de-select HW and then select CH. Boiler fired up and pump started immediately.

 

[ro63rto]

Just downloaded instructions for Horstmann timer.
Read about the HW Boost feature so tried it.
Checked boiler, had fired up this time and the (flow & return) pipes started getting hot.

Went to bathroom and touched the pipe that enters the cylinder half way up but it was cold. Shouldnt it be hot?

 

[Hugh Jaleak]

Still not 100% sure what type of system you have. If it is gravity HW/pumped CH, you cannot run CH independantly of the HW. The HW primaries allow flow from the boiler to the cylinder using gravity circulation, this (when working as it should) will allow flow from the boiler to the cylinder whenever the boiler is heating the water. HW selected on the timeclock will energise the boiler only, unless you have a 'C' plan whereby a motorised valve is fitted to the primary return to stall the gravity flow when cylinder is at temp. However, this would need a thermostat on the side of the cylinder to operate.

When CH is selected, HW will still heat by gravity circulation (as the boiler is also energised to fire), however the clock will also energise the pump to circulate the water around the rads. If you definately have gravity HW, then the flow into the cylinder should be hot if the boiler is working. Lack of circulation on the gravity circuit could be air lock or a blockage in the pipework.

Your 'Update' post is confusing though. If HW was selected I would expect the boiler to fire, even if only momentarily, to heat the water. Boiler should then shut down as heated water cannot circulate and is trapped in the boiler. When CH is selected, pump starts and begins to move the heated water, hence boiler fires again.

 

[xr4x4]

Gravity...

http://www.diynot.com/forums/viewtopic.php?t=5052

 

[ro63rto]

Still not 100% sure what type of system you have. If it is gravity HW/pumped CH, you cannot run CH independantly of the HW. The HW primaries allow flow from the boiler to the cylinder using gravity circulation, this (when working as it should) will allow flow from the boiler to the cylinder whenever the boiler is heating the water. HW selected on the timeclock will energise the boiler only, unless you have a 'C' plan whereby a motorised valve is fitted to the primary return to stall the gravity flow when cylinder is at temp. However, this would need a thermostat on the side of the cylinder to operate.

When CH is selected, HW will still heat by gravity circulation (as the boiler is also energised to fire), however the clock will also energise the pump to circulate the water around the rads. If you definately have gravity HW, then the flow into the cylinder should be hot if the boiler is working. Lack of circulation on the gravity circuit could be air lock or a blockage in the pipework.

Your 'Update' post is confusing though. If HW was selected I would expect the boiler to fire, even if only momentarily, to heat the water. Boiler should then shut down as heated water cannot circulate and is trapped in the boiler. When CH is selected, pump starts and begins to move the heated water, hence boiler fires again.

Just spoke to my brother. Confirms that HW & CH was available independantly but I have not seen any motorised valves anywhere.
One thing I noticed when I tried the boost button is the towel warmer in the bathroom heated up, so water is circulating, just not in cylinder. I'm getting more confused. Tomorrow I might try undoing the flow side of the coil and see if any air comes out as I read on other threads, unless there's a better way.
Definitely think the RDT mounted on the cylinder element needs replacing because when switched on and set to 50° you can hear it boiling if left on. Thought it should automatically switch off.

If anyone needs more info/photos I'll post them.

Thanks to all so far.

 

[Hugh Jaleak]

If the immersion is boiling the water in the cylinder it needs replacing ASAP! The thermostat should switch it off when set temperature is reached. Under fault conditions it has been known for an immersion to boil the contents of the cylinder, which in turn has boiled the contents of the cold storage cistern above which feeds the cylinder. These cistern's are often plastic, which can deform with the heat, dumping gallons of boiling water through the ceiling. There has been at least one fatality as a result of this, a young baby in a cot.

Can you put up some pictures of the primary connections to the side of the cylinder, will be two pipes, one at the bottom and another above it, preferably showing where they go and any other pipes connected. May be clearer if the lagging is removed first. If you have a gravity circuit on the HW the vent should rise from the flow connection to the cylinder, therefore no air should be trapped in the coil.

 

[ro63rto]

If the immersion is boiling the water in the cylinder it needs replacing ASAP! The thermostat should switch it off when set temperature is reached. Under fault conditions it has been known for an immersion to boil the contents of the cylinder, which in turn has boiled the contents of the cold storage cistern above which feeds the cylinder. These cistern's are often plastic, which can deform with the heat, dumping gallons of boiling water through the ceiling. There has been at least one fatality as a result of this, a young baby in a cot.

Can you put up some pictures of the primary connections to the side of the cylinder, will be two pipes, one at the bottom and another above it, preferably showing where they go and any other pipes connected. May be clearer if the lagging is removed first. If you have a gravity circuit on the HW the vent should rise from the flow connection to the cylinder, therefore no air should be trapped in the coil.

Thanks, didn't even think that could happen. Gonna change the RDT thermostat tomorrow.

The only photos I have are these. I can take more tomorrow. I'll take the new jacket off first though.

Primary connection halfway up cylinder.