Confusion - modulating boilers vs modulating controllers

[BriscsWK]

My understanding is that modern condensing boilers modulate to improve efficiency but I have come across a programmable room thermostat modulating controller (I believe Opentherm) and wonder how these would interrelate and whether it is preferable for efficiency to have both if it is an option?

Many thanks

Stuart

 

[Agile]

All modern boilers modulate!

Your confusion probably arises because you cannot visualise the flow temperature being externally controlled!

Tony

 

[BriscsWK]

I can imagine it being controlled externally - but if it isn't controlled externally is it then controlled internally and if so why the need for external control unless it is better?

 

[Agile]

Its always better to control it externally.

If its not controlled externally then its controlled by the knob on the front of the boiler!

I think you need to do some study!

Tony

 

[glasgowgas]

I can imagine it being controlled externally - but if it isn't controlled externally is it then controlled internally and if so why the need for external control unless it is better?

most modern HE boilers use a zero governor.when fired first thing when ch system is cold (20 deg C) boiler fan should ramp up to full speed clearing combustion chamber,ramp down to half this rate,fire, then,dependent on flow temp setting ramp up to full speed.
as it nears flow temp,fan ramps down(modulates) as you do not need to burn the same amount of full rate gas to raise water temp from say 70 to 80 deg C.

opentherm modulators are really weather compensators, if room stat set for 20 deg outside temp is 16deg, you dont need a flow temp of 82deg to raise room temp by 4 degs.
opentherm modulator over rides the flow temp setting to reduce the flow temp to what is needed to raise room temp.

look at vokeras website their controls section to maybe give you a better idea how they work

 

[simond]

Opentherm is an open weather compensation protocol. It alters the temp of water in the rads (if you have rads for instance) to the minimum necessary to heat the house. So on mild days your rads are only lukewarm, but on cold days they are very hot. This allows the boiler to save energy by condensing wherever possible.

Some manufacturers eg Worcester, Vaillant have proprietary weather compensation controls.

Others such as Broag have used Opentherm.

In principle Opentherm means you are not tied to the manufacturer for both boiler and controls. In practice the manufacturer proprietary controls often offer more facilities and are usually covered in the boiler warranty.

 

[D_Hailsham]

In principle Opentherm means you are not tied to the manufacturer for both boiler and controls. In practice the manufacturer proprietary controls often offer more facilities and are usually covered in the boiler warranty.

If you read the Vokera controls leaflet carefully you will find this in small print:

"Please note that the Vokèra Opentherm protocol only works with the above Vokèra boiler models and is not compatible with other manufacturers boilers."

So it is not true Opentherm, which is not surprising as the existing protocol only covers wired thermostats, not wireless.

PS Vokera is not listed as a member of the OpenTherm Association, though it's parent company Riello is!

 

[glasgowgas]

If you read the Vokera controls leaflet carefully you will find this in small print:

"Please note that the Vokèra Opentherm protocol only works with the above Vokèra boiler models and is not compatible with other manufacturers boilers."

So it is not true Opentherm, which is not surprising as the existing protocol only covers wired thermostats, not wireless.

was not suggesting to the OP to use Vokeras controls in his boiler,was merely pointing him to a site who could explain the principles of modulation and opentherm controls

 

[BriscsWK]

Thanks very much for all your replies - it's becoming clearer...slowly...

 

[bengasman]

If its not controlled externally then its controlled by the knob on the front of the boiler!

Or in my case:
If its not controlled externally then its controlled by the knob in front of the boiler!

 

[glasgowgas]

If its not controlled externally then its controlled by the knob on the front of the boiler!

Or in my case:
If its not controlled externally then its controlled by the knob in front of the boiler!

View media item 11522

 

[bengasman]

Don't worry, it's a southern thing.

 

[glasgowgas]

oh isee,

"whats the most dangerous part in a motor car"


"the nut behind the steering wheel"




and your last post is racist. im getting a human rights lawyer on yer ass immediately.


or i will accept a cheque of £50 to drop the case.

 

[bengasman]

and your last post is racist. im getting a human rights lawyer on yer ass immediately.


or i will accept a cheque of £50 to drop the case.

I've sent a check in the mail.

But if it's a female , like most human rights lawyers, send her anyway.

 

[glasgowgas]