I'm having trouble finding a decent diagram of how the diverter valve
works in a combi boiler.

I am assuming that there are two completely separate water flows through
the heat exchanger, only one of which is active.

The heating circuit water must be kept completely separate from the hot
water taps otherwise the chemicals in the central heating circuit would
leak out of the hot water taps over time.

However I can't find a diagram to show the complete flow.

I am mainly hitting descriptions of problems when the valve is faulty.


Cheers



Dave R


--
AMD FX-6300 in GA-990X-Gaming SLI-CF running Windows 7 Pro x64

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On 04/03/2018 14:40, David wrote:
I'm having trouble finding a decent diagram of how the diverter valve
works in a combi boiler.

I am assuming that there are two completely separate water flows through
the heat exchanger, only one of which is active.

The heating circuit water must be kept completely separate from the hot
water taps otherwise the chemicals in the central heating circuit would
leak out of the hot water taps over time.

However I can't find a diagram to show the complete flow.

I am mainly hitting descriptions of problems when the valve is faulty.


Cheers



Dave R


Have you tried Googling for a manual for your particular model? It will
probably be easier to identify the parts and the flow route from this.

On 04/03/2018 15:17, newshound wrote:
On 04/03/2018 14:40, David wrote:
I'm having trouble finding a decent diagram of how the diverter valve
works in a combi boiler.

I am assuming that there are two completely separate water flows through
the heat exchanger, only one of which is active.

The heating circuit water must be kept completely separate from the hot
water taps otherwise the chemicals in the central heating circuit would
leak out of the hot water taps over time.

However I can't find a diagram to show the complete flow.

I am mainly hitting descriptions of problems when the valve is faulty.


Cheers



Dave R


Have you tried Googling for a manual for your particular model? It will
probably be easier to identify the parts and the flow route from this.

This is the first hit that I get on a generic search

http://www.diydoctor.org.uk/projects/combis.htm

On Sun, 04 Mar 2018 15:19:29 +0000, newshound wrote:

On 04/03/2018 15:17, newshound wrote:
On 04/03/2018 14:40, David wrote:
I'm having trouble finding a decent diagram of how the diverter valve
works in a combi boiler.

I am assuming that there are two completely separate water flows
through the heat exchanger, only one of which is active.

The heating circuit water must be kept completely separate from the
hot water taps otherwise the chemicals in the central heating circuit
would leak out of the hot water taps over time.

However I can't find a diagram to show the complete flow.

I am mainly hitting descriptions of problems when the valve is faulty.


Cheers



Dave R


Have you tried Googling for a manual for your particular model? It will
probably be easier to identify the parts and the flow route from this.

This is the first hit that I get on a generic search

http://www.diydoctor.org.uk/projects/combis.htm

Thanks.

My GoogleFu is, as usual, sadly lacking.

So, if I am understanding this correctly, the primary heat exchanger
either heats the water for the central heating or heats the secondary heat
exchanger which in turn heats the hot water.

A bit like heating a hot water tank but much more concentrated and
instantaneous.

That makes sense (I think).

Cheers


Dave R


--
AMD FX-6300 in GA-990X-Gaming SLI-CF running Windows 7 Pro x64

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

On 05/03/2018 10:11, David wrote:
On Sun, 04 Mar 2018 15:19:29 +0000, newshound wrote:

On 04/03/2018 15:17, newshound wrote:
On 04/03/2018 14:40, David wrote:
I'm having trouble finding a decent diagram of how the diverter valve
works in a combi boiler.

I am assuming that there are two completely separate water flows
through the heat exchanger, only one of which is active.

The heating circuit water must be kept completely separate from the
hot water taps otherwise the chemicals in the central heating circuit
would leak out of the hot water taps over time.

However I can't find a diagram to show the complete flow.

I am mainly hitting descriptions of problems when the valve is faulty.


Cheers



Dave R


Have you tried Googling for a manual for your particular model? It will
probably be easier to identify the parts and the flow route from this.

This is the first hit that I get on a generic search

http://www.diydoctor.org.uk/projects/combis.htm

Thanks.

My GoogleFu is, as usual, sadly lacking.

So, if I am understanding this correctly, the primary heat exchanger
either heats the water for the central heating or heats the secondary heat
exchanger which in turn heats the hot water.

A bit like heating a hot water tank but much more concentrated and
instantaneous.


Correct. One weakness of Combis, particularly if there is corrosion in
the intermediate circuit, is that the DHW heat exchanger may become
blocked, and then you get inadequate temperature and/or flow in your DHW.

On 04/03/2018 14:40, David wrote:
I'm having trouble finding a decent diagram of how the diverter valve
works in a combi boiler.

I am assuming that there are two completely separate water flows through
the heat exchanger, only one of which is active.

The heating circuit water must be kept completely separate from the hot
water taps otherwise the chemicals in the central heating circuit would
leak out of the hot water taps over time.

However I can't find a diagram to show the complete flow.

I am mainly hitting descriptions of problems when the valve is faulty.


Cheers


Try YouTube.




--
Adam

On Sunday, March 4, 2018 at 2:40:12 PM UTC, David WE Roberts (Google) wrote:
I'm having trouble finding a decent diagram of how the diverter valve
works in a combi boiler.

I am assuming that there are two completely separate water flows through
the heat exchanger, only one of which is active.

The heating circuit water must be kept completely separate from the hot
water taps otherwise the chemicals in the central heating circuit would
leak out of the hot water taps over time.

However I can't find a diagram to show the complete flow.

I am mainly hitting descriptions of problems when the valve is faulty.



There are typically two heat exchangers. One (CH) for gas/circui****er and another (DHW) or circui****er/domesticwater. THey have different designs. The diverter valve switches the circui****er flow between the DHW or the radiators.

RObert

David wrote:

I'm having trouble finding a decent diagram of how the diverter valve
works in a combi boiler.

I am assuming that there are two completely separate water flows through
the heat exchanger, only one of which is active.

The heating circuit water must be kept completely separate from the hot
water taps otherwise the chemicals in the central heating circuit would
leak out of the hot water taps over time.

However I can't find a diagram to show the complete flow.

I am mainly hitting descriptions of problems when the valve is faulty.


Some combis have a separate heat exchanger for hot water which has
pumped hot water from the main heat exchanger (the same water as can be
used for circulating to the radiators) on one side, and the mains water
supply being heated on the other side. So the main heat exchanger
heated by the boilder flame has only one water flow.


--

Roger Hayter

On 04/03/2018 14:40, David wrote:

I'm having trouble finding a decent diagram of how the diverter valve
works in a combi boiler.

I take it you mean a flow / hydraulic diagram rather than circuit?

I am assuming that there are two completely separate water flows through
the heat exchanger, only one of which is active.

Not usually. (there are a few boilers that use the main HE to heat the
water for the taps as well - however they are rare)

The heating circuit water must be kept completely separate from the hot
water taps otherwise the chemicals in the central heating circuit would
leak out of the hot water taps over time.

That's right

However I can't find a diagram to show the complete flow.

There are typically two separate heat exchangers. The primary HE, has
the CH water flow through one side, and has the other side heated
directly by the gas flame.

There is a secondary (smaller) water to water cross flow heat exchanger
that is used to heat the hot water for the taps.

When heating the rads, the primary water (plus inhibitor etc) flows
through the main HE, the pump, the rads, then back again.

When there is a demand for hot water (usually sensed by a flow switch),
this activates the diversion valve. It the switches the output from the
main HE so that it now flows through the secondary HE rather than the
rads. Thus creating a short loop for the primary water that runs through
the main HE, pump, and the secondary HE, and then back to the main HE.

So the main HE is ramped up to full power, that heats the primary water,
which in turn heats the mains cold water flow through the "other" side
of the secondary HE.

I am mainly hitting descriptions of problems when the valve is faulty.

Typically if it fails to operate, turning on a tap will cause the boiler
to fire, but instead of the water getting hot, it will just start
heating the rads instead.

--
Cheers,

John.

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