Buderus FM446 setting

[marvinek]

Hi,

I'm from Slovakia and my German isn't that perfect som I will write in English.

I have Buderus FM446 module in operation and I'd like to ask how should I set the parameters 'Delta Vorlauftemperatur, untere grenze' and 'Delta Vorlauftemperatur, obere grenze' in Heizkreis parameters. I have 2 Heizkreise - 1. FBH and 2. classic radiator HK. According to the type of Heizkreis I set the Verstarkungsfaktor. The Sollwert der. max. Ventilstellung I set to 50%.

Can anybody help me?

regards
m.

[tbi]

Hi Marvinek,

mmh, many reads and no comment. What is your real problem with the module.

Best Regards
Tbi

PS: English is no problem here

[marvinek]

The question is how should I set the 'Delta Vorlauftemperatur, untere grenze' and 'Delta Vorlauftemperatur, obere grenze' parameters in FM446. Is it dependent on type of Heating (floor or radiator) for particular heating circuit? Or is it dependent on setting of RTR? The description in Buderus guide is unclear (for me).

regards
m.

[tbi]

Hi,

first question: You wrote:

I have 2 Heizkreise - 1. FBH and 2. classic radiator HK.

Buderus understand Heizkreises as part of the heating system which has an own VL Temperatur (this need at least a motor controlled mixer per Heizkreis).

In this case the main control has 2 Heizkreise and they can be controled seperat. The main heating Unit should have in this case a bit hieher VL temperatur cause the mixer can one mix down.

If your plant is like this you can setup in the EIB Part also 2 Heizkreise.

One for FBH with EIB RTR „komplett mit EIB-Raumregler“. If this is true that the FBH has only EIB RTR with controled valves. (The FM446 work here with pos AND neg. influence on the VL. The both parameter you have in questions are only delimiters of the delta VL.)
and
one for konventional heating this would be controlled by outer temperature VL in old fashion.

Here you can set parameter as suggested in the manual.

All these base on the assumption you have realy motor driven mixer and a own VL there.


On the other case (no motor driven mixer) you have only one Heizkreis. This whould then be a mixed one „Kombination EIB-/konventioneller Raumregler“. In this case the VL doesn't be influenced by decrease. Only in increase cause only the have part is known by the system.
Here only positive delimiter will be effective.

This leads to question, which "Verstärkungsfaktor" should be used. Cause the FM446 will only change in positive VL for the FBH, this would be the value for the FBH 0,3 as I remember.

https://www.buderus.de/sixcms/media....446%202003.pdf

https://www.buderus.de/sixcms/media....ung%202003.pdf

Does this help ?

Tbi

[marvinek]

Both 1.FBH as well as 2.clasic radiator have independend pump and motor controled mixer. All rooms have their individual EIB RTR and both HK are in FM446 set as 'komplett mit EIB-Raumregler'. "Verstärkungsfaktor" is set according to Buderus advice https://www.buderus.de/sixcms/media....ung%202003.pdf. RTR are set as 1byte continous control value with converting to PWM.

Im still not sure about setting of these two Deltas. If I have it set -10 for Untere Grenze and +30 for obere Grenze, is it ok? Should be the same for FBH and konventional?
Probably I start to undersand these parameters ... VL is calculated accourding to outer temperate and heating curve and then (after calculation of EIB control influense) if VL should be raised(lowered) these are the limits - VL won't be lowered less than (-10), or raised more than (+30)? Is my understanding correct?

thx
m.

[tbi]

the limiter of the "Delta" or EIB "influence"

Hi,

nearly. This is the limiter of the "Delta" of the "influence". This enshures that the control doesn't make swinging. This can occur if the Delta is too big.

If you set the values lower you get a slower reach of wanted target VL for the Heizkreis. If you set them to high, you will see swinging of the IST VL around the target VL temperature. If you take the suggested default values, I thing every thing would be fine.

If you see problems make the values lower.

Regards

Tbi

[marvinek]

ok, I will try -10 and +10 and I will monitor it for a while.

regards
m.

[tbi]

You can see in Abbildung 3 on page 6 in
https://www.buderus.de/sixcms/media....446%202003.pdf

what you do. You limit the value

dTVL

(Aufschaltung auf Vorlaufsollwert

über Heizkennlinie)

but this limits also your EIB influence to the VL. So -10 and +10 could be a bit too small.

If you set both to zero, you don't have any influence from EIB.

In this case your VL is complete driven by the outer temperature and Heizkreiskurve.

Best Regards

Tbi

[marvinek]

I think now it's clear (hopefully) - it's the limitation of the influence of EIB control on VL value calculated from outside temperature. If this parameter is to small the influence (dTvl) is limited and the control is more 'managed' by 'native' Buderus controlling. If it's to high the impact on VLsoll for particular cicruit is significant (less limited). And then if changes on VL calculated from EIB are high the VLsoll oscillate significantly (based on less-limited dTvl).

Am I right, that for FBH is better to have more limited influence (e.g. +-15) and for classic less (+-30)?

thanx
m.

[tbi]

deltas on VL on FBH should be lower

Hi,

to your question. In general is the mainmal VL for FBH lower then as for classic ones. Let's say VL_max for FBH is 55 and classic is 70.

Then it is clear that deltas on VL on FBH should be lower than as for classic.

I see you have understud well. I am shure you will find now the proper setting for your plant.

Regards

Tbi

[Gaston]

Hi,

I would assume that you have a condensation heating ? In that case you don't have to worry about any flow temperature (Vorlauftemperatur) swinging.

In my case I have left the Delta at the default values -20/+40°K for both floor heating and radiators. It may seem logical to use smaller values for the floor heating because of its overall lower flow temperature but if you use the correct values for the amplifier parameter (Verstärkungsfaktor, 0.3 for floor heating, 0.6 for radiators) this is kompensated there not via the limits.

You may consider the "Verstärkungsfakor" being the technical Parameter and the influence limits the komfort parameters. For example having the flow temperature regulated to 30°C using the outside temperature and a maximum of 45°C.

In this case as long as the upperlimit is above or equal 15°K you will always have 45°C at 100% valve positioassuming Vmax,soll=50%, Vp=0.3) regardless of th eupper limit set. So in this scenario there is no difference in setting he upper limit to 40,20 or 15, with 10°K of course the plimwl be cut at 40°K. The limits are not used in the regulator computation, only limiting its influence, i.e. limiting the comfort when heating up a room.

Note that these limits will never overrule the system limits. So if a circuit is set to max 45°C, this will limit the temperature of course in th eexample above even if the upper limit was set to +40°K (30+40 would be 70°C).

Also there is no energy win by limiting the influence as the additional loss due to the higher temperature will be compensated by the shorter time used to heat up the room with the higher temperature.

Bets regards,
Gaston

[marvinek]

Hi,

thank you for the explanation.

I have GB142 condensation heating as you assumed.
The Verstärkungsfaktor I set according to Buderus advice (0,3 for FBH; 0,6 for radiators), VLsoll,max is 50% and there is as well security temperature element on FBH circuit (in the case of any failure in controlling it breaks the mains to pump above 55°C).
PWM cycle time I have set to 35mins for FBH and 17.8mins for radatiors. In some rooms I use 2-step heating where FBH is as main and radiator as aditional heating. Both with 1-byte - 0-100% control. Aditional heating has hysteresis od 0.5K.

regards
m.