Energy savers reports

[JohnD]

An interesting thought

I have a Vitodens 100 Compact, and annoyingly, Viessmann say their more whizzo controls do not work with it (maybe it has a simpler PCB for the UK market)

However my house is pretty well insulated and I will need to go through a winter to see if I think more complexity is worthwhile for controlling the "early morning start"

So far, when I gave been away for a weekend and the house has got chilly, it gets comfortable in about half an hour, the boiler modulates down and the TRVs start to close (and I suppose the pump must modulate down too) and the room stat is satisfied within an hour. But so far indoor temps have not been below 15C and outoor temps (overnight) not below 6C.

On sunny days here there is quite a lot of solar gain until dusk.

 

[D_Hailsham]

It appears there is confusion between an optimiser (delayed start) and a weather compensator.

I'm not confused

Optimisation is different to delayed start. Optimisation will delay the boiler's start to reach the start occupation time temperature setpoint and "increase" it too.

Not sure what you mean by "increase"

The better versions will optimise the off period too (it works out when to turn off the boiler to keep the room setpoint constant right up to the off time).

But surely the thermostat does the same job. Say the room is up to temperature half an hour before turn off time, the room looses heat at a rate of 1/2 degree per hour and the thermostat has a differential of 1 degree. For all intents an purposes the boiler will be off for that last half hour. Nothing clever about that.

If the building is at setpoint, even at the start of occupation time, some will still keep the heat off. The simpler versions will always bring on the heat at the start of occupation time.

But that is up to the thermostat. if the room is up to temp at start the thermostat will be open and the boiler will not light.

Delay start is just that, it only delays the start and always brings in the heat at start of the occupation time.

What, even if the thermostat says there is no need for heat?

Weather compensation is varying the flow or return temperature depending on the outside temperature. The lower the outside temperature the higher the flow or return temperature (some sense the flow temperature, others the return). The flow or return temperature can be trimmed up or down with room temperature influence to maintain a room temperature setpoint.

It may measure the return temp, but the only thing it can influence is the flow temperature. What it is effectively doing is altering the output of the radiators to meet the demand.

If the weather compensation and delayed start are separate units, there should be no problems, condensing boiler or not.

That confirms what I thought.

I also agree about Opentherm. Another boiler you can add to your list is the Broag Remeha Avanta range.

 

[BigBurner]

Not sure what you mean by "increase"

Many have a maximum warm up time, say 2 hours. Some can go over this.

But that is up to the thermostat. if the room is up to temp at start the thermostat will be open and the boiler will not light.

The optimiser keeps the heat off. In commercial systems where there are many zones one zone maybe below setpoint (senors not stats), if many are above then it will keep the burner off. Some "average" the temperature of say 4 room sensors.

Some optimisers only operate on say, a valve bringing in heat from a Boiler loop. The boiler may be on for DHW purposes. Some weather compensators modulate a valve, which is the norm in commercial systems. A combined optimiser/weather compensator will operate and modulate one 3 way mixing valve. There may be many of these operating heating zones on say the north and south side of a building - one subject top solar gain, the not. Landis & Staefa have a solar sensor to drop the flow temperature depending on the suns intensity.

I also agree about Opentherm. Another boiler you can add to your list is the Broag Remeha Avanta range.

Stands to reason as it is Continental. That is a well priced boiler too - although kit with the main parts seen in many boilers. The price and OpenTherm would slant it for me. Not sure about parts and service, as pretty new in the UK in the domestic market.

 

[mehran]

just to add to the list of open therm boilers

the heat-line vizo plus and the new heat-line Sargon, they also take outside temp sensors. my guess the likes of viessmann and that don't want to make the boilers open therm as they want to sell own brand controls to us.

 

[simond]

We fitted a Broag Avanta late last year in Sussex with opentherm weather comp, (in fact our installation appeared in a two page feature in Plumbing and Heating Monthly if anyone wants to look!). Some of the photographs in the current Broag brochure are also from that job.

Works very well, and the controls are third party and easy to use. The three port on/off zone valve is difficult to get hold of; it is biased the other way to the usually stocked Honeywell variant over here. After finding there were none in the UK a head teccy at Broag advised us that there was a changeover relay terminal not mentioned in the instructions, allowing the more common Honeywell valve type to be used.

Heat exchanger in the Broag baby boilers is the stainless Giannoni Thermionic as found in many others including Vaillant.

 

[BigBurner]

Three points

1. You have had failures and the parts were difficult to get hold of? A 3-way valve in such a short time does not sound too good.

2. Any detail of this mod to get a standard Honeywell 3-way vale working?

3. Where the controls third party Opentherm, or supplied by Broag?

 

[Agile]

Can anyone tell me whats in the WC kit for the Votodens 100 combis?

Is it just a sensor ( what resistance ? ) or more?

Tony

 

[D_Hailsham]

The three port on/off zone valve is difficult to get hold of; it is biased the other way to the usually stocked Honeywell variant over here.

I assume you talking about the three port diverter valve (V4044), not the mid position valve (V4073). In which case, why not turn the valve round! The orientation of a mid-position valve is important in a Y-plan, but the orientation of a diverter valve is not importan. So if you want the port feeding the CH to be open when the diverter valve is un-powered, just turn it round so the CH is fed from port B.

Or am I missing something?

 

[WDIK]

twaddle.
the optimiser compensator, has been around in many forms for decades, recently introduced as a weather compensator to the domestic market, just to confuse plumbers

optimisation

a set point is set, an anticipation algorythm is preset according to degC per degC outside temp compared to degC inside temp.
the algorythm calculates a warm up ramp to predict pre heat start time and rate per hour per degG to achieve desired inside temp at set time.

and in reverse ramp down to off prior to end of occupation time.

during occupation time the inside and outside sensor readings operate the compensator algorythm as per the desired inside setpoint.
and predicting the flow temp to acieve the desired inside set point.

pretty simple been around for at least 3 decades, first developed by a guy called Jel, funny i was a Jel BMS engineer.

 

[BigBurner]

twaddle.

What do you think is twaddle?

BTW, Honeywell, and English fellow actually, invented the Optimiser.