No Hot Water

[gcc]

Hi
New to the forum, would appreciate some guidance on a problem with my central heating
Background...Recently had the system drained to fit a new towel rail and re-route some pipe work, also flushed out some of the debris etc. Thats the only change which has occurred.
Boiler is a fairly old thing but works ok its and Ideal Mexico.
System is fully pumped.
Two electornic valve switches are present both two port, one which is on the feed to the radiators downstairs and the other to the upstairs. Heating can be isolated to upstairs or downstairs or both. Hot Water is on constantly with heating weather up or downstairs is on so no switches on the primary circuit.
Hot water can be on independantly without central heating
Problem.. When we switch on just hot water, the boiler fires up but the pump isn't working so no hot water. If I turn on the central heating the water then heats up and the pumps working.

I have checked the controller by replacing it with another and still nothing. I don't think the electoric vavle switches affect this as they don't run on the central heating circuit although I have checked them and even went as far a s dummy wiring a new one in the circuit (I have a new spare for this) to make sure in case the microswitch was affecting it in any way,

Any ideas anyone has greatfully received.

Update
Took off the two way valve, drained system as the valve is an old version.
cleaned and made sure it was working ok.
Back on refilled and still no joy!
any ideas why the pump isn't working on hot water alone?

 

[Jimbob]

well are you saying the primary circuit to hot water cylinder in on a constant loop and is not controllers by a 2 ports valve. Is there any kind of thermostat on the hot water cylinder? Also does the boiler have pump over run ? it would be wired from the boiler if it had.

when the heating circuits are switched on, the switch makes the 2 ports valve open, which flicks a microswitch which sends power to boiler and pump. Its hard to say but somehow you boiler is being fed without the pump being fed, i would start off seeing how the pump is wired in, It would usually be wired in commonly with switching feed to boiler. If your not confident with wiring, dont touch it because it can be a nightmare!

I would update the system so that the hot water circuit is fully controlled with a 2 port valve and cyl stat and wired in accordingly, doing this would bring it upto modern requirements.

James

 

[Puddle]

Well it could be your hot water is gravity as old system,if this is the case then usually the towel rail will be included in gavity hot water pipe run, if you have altered pipwork you could have upset something in this run ,as you get hot water when heating/pump on should not be air locked
But as Jimbob says you should think about updating system

 

[stevetheplumber]

sounds like the hot water primary circuit is gravity fed when you say its not working is the boiler lighting and then going of when you select hot water only ? if so it sounds like you have an airlock in the primaries
crack open the top connection on the primary side of the cylinder and see if there is water there

in this type of system the clock sends power to the boiler only for hot water no pump needed

 

[gcc]

Thanks chaps
I managed to trace through the wiring...which was a nightmare..as you said ..have now wired the pump to come on with the boiler when hotwater is selected. This has cured the problem. Pump now firtes up with the boiler and hey presto hot water!
The towel rail I fitted replaced a couple of radiators which were on a sperate feed using micro piping under the concrete floor. I have disconnected that piping and continued with 15mm piping through the adjacent wall to the towel rail which seemed the logical solution. This feed gets hot with the hot water whilst the other radiators in the house do not? Is this the pump overun?

As far a control valves go, there is one on the feed which supplies the radiators this is a standard Honeywell 2 port affair which I have replaced the motor on as a matter of course, whilst troubleshooting, also took it apart and cleaned it etc. The only other valve is another two port which controls the upstairs rads and is sited uder the upstairs floorboards. There is nothing on the pipework to and from the copper tank and the tank has no thermostat. The only stat on the system is the frost one in the room with the boiler.

It is a fairly big system with 18 rads/towel rails.
The boiler I know is an antique and needs to go. I have flushed the system and done each radiator as I decorated rooms taking each one off and flushing through etc. The heating is effective but the hot water has never been good and the costs are through the roof!

What would you chaps suggest in the way of a new boiler and set up? We have a fairly low water pressure. The two showers are electric fed by a pump and seperate tanks in the loft to assist. The bathrooms are a long way from the boiler so hot water takes a while to appear.
So I really need a good boiler for hot water and heating
Am going to get a professional in (on recommendation) to have a look and give me ideas and a quote but would be grateful of some pointers?
Thanks again for the help