Boiler does not turn on for hot water

robshak

matt_drummer said:

FreeBear said:

matt_drummer said:

You should have a wiring centre somewhere that your programmer is connected to.

The wiring centre is probably that white box on the floor in front of the boiler. But invariably, none of the wires will be labelled, and they'll all be one of three colours.

There might be a wiring diagram inside the cover?

That's what's in the box. The white cable goes to the boiler. Don't know what are those feeds marked P, 1 and S/5. box

Qyburn

The five core black sheath are the valves.

Are we sure this is a combi boiler?

QrizB

Qyburn said:

The five core black sheath are the valves.
Are we sure this is a combi boiler?

It's definitely a combi boiler, but it's being used as a system boiler.
This seems to be confusing a few people.

FreeBear

QrizB said:

Qyburn said:

The five core black sheath are the valves.
Are we sure this is a combi boiler?

It's definitely a combi boiler, but it's being used as a system boiler.
This seems to be confusing a few people.

If you look at the last picture of the boiler internals, there appears to be just three pipes going out of the bottom. One gas, one flow, and one return. I'm fairly sure it is a system (heat only) boiler (Greenstar 30CDi ?). No DHW heat exchanger visible either.

QrizB

FreeBear said:

QrizB said:

Qyburn said:

The five core black sheath are the valves.
Are we sure this is a combi boiler?

It's definitely a combi boiler, but it's being used as a system boiler.
This seems to be confusing a few people.

If you look at the last picture of the boiler internals, there appears to be just three pipes going out of the bottom. One gas, one flow, and one return. I'm fairly sure it is a system (heat only) boiler (Greenstar 30CDi ?). No DHW heat exchanger visible either.

Didn't glennevis identify the internal CH/DHW valve on the previous page?
Also, the boiler has a knob to set the DHW temperature, which you wouldn't expect to see on a system boiler? (I could be very wrong here, I've got a regular boiler not a combi or a system.)

FreeBear

QrizB said:

FreeBear said:

QrizB said:

Qyburn said:

The five core black sheath are the valves.
Are we sure this is a combi boiler?

It's definitely a combi boiler, but it's being used as a system boiler.
This seems to be confusing a few people.

If you look at the last picture of the boiler internals, there appears to be just three pipes going out of the bottom. One gas, one flow, and one return. I'm fairly sure it is a system (heat only) boiler (Greenstar 30CDi ?). No DHW heat exchanger visible either.

Didn't glennevis identify the internal CH/DHW valve on the previous page?
Also, the boiler has a knob to set the DHW temperature, which you wouldn't expect to see on a system boiler? (I could be very wrong here, I've got a regular boiler not a combi or a system.)

Speculating here - The internal diverter valve is there for a Y plan system, and there would be a thermostat on the tank linked back to the boiler. This would allow the boiler to control DHW temperature as well as the CH. The extra zone valve between the boiler & tank would be redundant. A photo of the pipework coming out of the bottom of the boiler would confirm.

Also have a combi here - I can set the CH and DHW temperatures from the front panel, but i have a smarter control system that controls all that stuff.

Qyburn

QrizB said:

Qyburn said:

The five core black sheath are the valves.
Are we sure this is a combi boiler?

It's definitely a combi boiler, but it's being used as a system boiler.
This seems to be confusing a few people.

It's confusing me, but if the DHW is being heated by conventional pump, valve, tank etc then surely the combi function is irrelevant. And it doesn't matter whether the diverter works or doesn't work. If it supplies hot water to the heating system, but doesn't to the tank then that's a problem external to the boiler.

Pump is OK as thats common to both. So could be valve, cylinder stat or programmer.

Tests have been suggested for each of these, but not carried out, so I'm not sure why we're assuming the fault is internal to the boiler 

robshak

FreeBear said:

QrizB said:

Qyburn said:

The five core black sheath are the valves.
Are we sure this is a combi boiler?

It's definitely a combi boiler, but it's being used as a system boiler.
This seems to be confusing a few people.

If you look at the last picture of the boiler internals, there appears to be just three pipes going out of the bottom. One gas, one flow, and one return. I'm fairly sure it is a system (heat only) boiler (Greenstar 30CDi ?). No DHW heat exchanger visible either.

Spot on FreeBear, it is a Greenstar 30CDi..a few more photos to demystify things a bit..

Last photo - 1 is vent, 2 is gas, 3 is outlet, 4 I think is inlet because it is connected to tap you add in water to increase pressure.

I also ran a live feed check with programmer on for DHW on and my findings are:

- Cable P, assuming from programmer passes live feed to HW tank, I followed cable, hence cylinder thermostat has live feed.

- Boiler white core brown cable takes live feed from pink wires from silver boxes black cores. This is dead.

- Sliver boxes take live feed through grey cables connected to live brown from 1. This is live.

- It seems current disappears once it goes into silver boxes via grey cables but doesn't come out via pink cables to pass it to the Boiler. 

- Also 5/S is dead.

Phew!! That test pen was a God send!!

robshak

Qyburn said:

QrizB said:

Qyburn said:

The five core black sheath are the valves.
Are we sure this is a combi boiler?

It's definitely a combi boiler, but it's being used as a system boiler.
This seems to be confusing a few people.

It's confusing me, but if the DHW is being heated by conventional pump, valve, tank etc then surely the combi function is irrelevant. And it doesn't matter whether the diverter works or doesn't work. If it supplies hot water to the heating system, but doesn't to the tank then that's a problem external to the boiler.

Pump is OK as thats common to both. So could be valve, cylinder stat or programmer.

Tests have been suggested for each of these, but not carried out, so I'm not sure why we're assuming the fault is internal to the boiler 

Hi, as someone suggested earlier correctly, the only HW output from boiler is split into two, one feeding the CH and other going into the HW tank to heat the water..

The only advantage I see for this system to heat hot water for taps is that the boiler does not have to heat water separately for taps and because of the tank, it keeps it warm for longer (otherwise, the boiler would fire up every time we demand hot water).  Is this right? May be efficient this way?

[Deleted User]

Forgive me if this has been mentioned before. The OSO RI series of unvented cylinders have a built in cylinder thermostat. It sits behind the screwed metal plate. It might be worth TURNING THE HOUSE POWER OFF; unscrewing the plate to see if the thermostat needs to be reset.

If that doesn’t work, then any remedial work undertaken on an unvented cylinder must be carried out by a G3 annotated Gas Safe engineer. Unvented cylinders have three levels of thermal safety built into them to prevent any possibility of explosion.

https://youtu.be/61uDmQF5I2E?si=Dxa3qyE9n-yiMhck