On 22 Feb, 17:14, "Dave Plowman (News)" wrote:
In article ,
geoff wrote:



In message , "Dave Plowman (News)"
writes
In article ,
geoff wrote:
In message , "Dave Plowman (News)"
writes
In article
,
Vet Tech wrote:
Modern condensing boilers are supposedly designed to modulate the
heat output. Am I correct in thinking that this modulation
depends on the temperature of the return water temperature and/or
the setting on the cylinder thermostat. My query is just how
accurate and efficient is this control process? Is it a stepped
process or truly linear.? For example, say its a summer's day and
the CH is not on so all the boiler has to do is keep the hot water
cylinder at the right temperature. You are all out that day so
there's no real demand for hot water. When the timer swithes it
on, the boiler presumably fires up and gradually brings the water
temperature back up to the temperature of the thermo stat on the
cylinder. Can it modulate the gas consumption down progressivley
within fine limits eg 5% or is it a fairly rough comprimise eg
down to 25% until switching off when the thermostat limit is
reached. Incidentally, I have a Vaillant EcoMax Pro.

It should keep the boiler running at its highest efficiency until
the desired temperature is achieved then switch off.

Well, no

Think of the hysteresis

Modulation is primarily to keep the hot water constant. Being now
"office bound" and not actually doing any testing myself anymore - I
don't know

Vaillant have used both methods in the past, I think the EcoMax is
stepped (crudely so, IIRC)

I didn't think we were talking about a combi.

http://www.wholesaleheating.co.uk/vaillant-boilers.html

The OP seems convinced he has a storage cylinder.

--
*If you can't see my mirrors, I'm doing my hair*

Dave Plowman London SW
To e-mail, change noise into sound.

The ecomax pro is a regular boiler, the ecoTEC pro is a basic combi
boiler.

In message
,
David writes
On 22 Feb, 17:14, "Dave Plowman (News)" wrote:
In article ,
geoff wrote:



In message , "Dave Plowman (News)"
writes
In article ,
geoff wrote:
In message , "Dave Plowman (News)"
writes
In article
,
Vet Tech wrote:
Modern condensing boilers are supposedly designed to modulate the
heat output. Am I correct in thinking that this modulation
depends on the temperature of the return water temperature and/or
the setting on the cylinder thermostat. My query is just how
accurate and efficient is this control process? Is it a stepped
process or truly linear.? For example, say its a summer's day and
the CH is not on so all the boiler has to do is keep the hot water
cylinder at the right temperature. You are all out that day so
there's no real demand for hot water. When the timer swithes it
on, the boiler presumably fires up and gradually brings the water
temperature back up to the temperature of the thermo stat on the
cylinder. Can it modulate the gas consumption down progressivley
within fine limits eg 5% or is it a fairly rough comprimise eg
down to 25% until switching off when the thermostat limit is
reached. Incidentally, I have a Vaillant EcoMax Pro.

It should keep the boiler running at its highest efficiency until
the desired temperature is achieved then switch off.

Well, no

Think of the hysteresis

Modulation is primarily to keep the hot water constant. Being now
"office bound" and not actually doing any testing myself anymore - I
don't know

Vaillant have used both methods in the past, I think the EcoMax is
stepped (crudely so, IIRC)

I didn't think we were talking about a combi.

http://www.wholesaleheating.co.uk/vaillant-boilers.html

The OP seems convinced he has a storage cylinder.

--
*If you can't see my mirrors, I'm doing my hair*

Dave Plowman London SW
To e-mail, change noise into sound.

The ecomax pro is a regular boiler, the ecoTEC pro is a basic combi
boiler.

From the link

"Vaillant ecoMAX combi boiler

The ecoMAX range of condensing boilers ..."

I thought it was a combi too

--
geoff