Vitodens with Zone Valves

Simply Rad_2

Allow the Vitodens to control your system pump it works with constant circ and shuts off on WWSD. Sensor should be inside the box. Make sure you follow the Sart and service guide. Follw each one and the system will purr like a kitten and not a lion. I would recommend going to Viessmann academy schools. They are the best.
Jeffrey

Man with a question

Control Strategies with Vitodens 200

I am in the middle of a boiler replacement using a Vitodens 200. It is the first time I have used one of these beauties and I am a little confused about one issue.

I have the Boiler Control Module and the Domestic Hot Water kit. So there are provisions for firing the boiler, activating the DHW pump for the Indirect etc. What I am confused about is how to incorporate the Zone Valves for the Radiant Zones.(There are 6)

Normally I use a Taco Zone Valve Control which gets the signal from the thermostats, then triggers a pump relay and fires the boiler when an end switch closes.

How does this mesh with the Vitodens 200 onboard controls? How does the Vitodens know a Zone Valve is open and that it's showtime?

Is there a provision to wire the zone valves directly to the Vitodens' Controls and do away with ZVC completely.

I know there are those out there who KNOW.

Help and advice much appreciated.



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joel_19

Vitodens

Vitodens runs on reset it doesn't care if the zones calling or not it's always "show time"

Mike T., Swampeast MO

The Vitodens is single-minded. It ONLY wants to produce the target temperature in the most efficient manner possible.

As the zone valves open and close it takes more or less energy to maintain the target temperature--it really is that simple (in theory).

For the highest efficiency you want to establish a target curve that keeps all of the zone valves open as much of the time as possible.

S Ebels

"How does this mesh with the Vitodens 200 onboard controls"?

It doesn't basically. The Vitodens onboard circ runs based on outside air temp and other control inputs you program into it. If your careful with your piping and keep the head down, you may be able to use the Vitodens pump alone but again, you would REALLY want to know exactly what head is in each of your zones. If that is do-able you would want to install a pressure bypass valve to allow the circ some flow if/when all the ZV's are shut because you can't turn it off in the normal manner you're used to.

Another way to handle the scenario would be to use the onboard circ a "primary loop" circulator and then install your standard ZV control and another circ just as you would on a regular boiler. Viessmann make a device called a Low Loss Header that will hydraulically seperate the boiler pump from the system also. Check out your installation manual, it's in there.

"Is there a provision to wire the zone valves directly to the Vitodens' Controls and do away with ZVC completely."

No. The Vito is designed along the European model/style of heating where the circ and hence flow, runs constantly. Temp regulation is done by changing water temps, not stopping flow. This requires a new line of thinking sometimes as far as control strategy's are concerned.
In instances where you have a significant difference in heat load room to room you have to implement something along the lines of your typical ZV setup.

If you use the ZV panel you can use the system pump output on the Pump Module as the input for the relay on it (ZC I think)
There are a host of ways to do it but the basic's are covered in the installation manual. Take your time and ask lot's of questions, get in touch with your rep and ppick his brain or call Viessmann, they'll be happy to help.
The first on can be a little confusing due to different methods used.

Cosmo_3

NO CONNECTION!

Yeah, sounds crazy eh?

But believe me it works like a charm! Read your manual, and you can guess a heating curve based on your radiation. Then tell your customer that you will have to come back a couple times to adjust this curve. I was fortunate enough to have my systems running in a finished house as the final painting/ moving was being done and was able to dial it in without bothering the homeowner.

Don't be afraid to call Viessmann, they know their product and are an extremely valuable resource.

Cosmo

Man with a question

Glad I asked.

So let me get this straight.

The boiler is designed to run more or less constantly according to the outdoor reset curve?

Is there even a warm weather shut down? Bear in mind, a design day here is 39 degrees. It is often 70 out by 1PM, even in winter.

I have the system designed thus.

I have a high head/flow (grundfoss 26-99) pump to the 120GL indirect.

I have a primary loop servicing 6 radiant zones with Taco ESP zone valves. That pump I believe is a 25/64. I have nice 1 1/4" primary loop lines. I did indeed install a pressure differential bypass. On a cold day (cold for us) I want about 115 degrees delivered to the floor.

Is the water going to circulate constantly on a temp defined by my reset curve? Say 75 to 130 degrees. How is that efficient?

I found an outdoor reset sensor housing in the Boiler Package, but no sensor. Is it a simple 10K ohm sensor? I have plenty of those around.

Do I also understand that there is an onboard circulator in the 15-60?

In the control manual I believe #20 is the boiler circulator which I took to be the Radiant loop circulator.

If it is not, what triggers the prim loop circulator? Is that where the ZVC comes in.

By the way, what are two barbed fittings inside the boiler. It appears to be some kind of bypass.

I guess everyone has to have their first one. Certainly appears to be an outstanding boiler and I am in the right market to sell them.

Showed a client the Vitodens and a Trinity side by side today, explained the differences in price and build. Shut my mouth and smiled. They chose the Vitodens instead of the Trinity and the equivalent of a weeks vacation for two in Cabo San Lucas. Gave me a very warm fuzzy...


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Simply Rad_2

Vitodens Rocks!

The Vitodens is a very powerful system NOT just a boiler It has the ability to control your system and then some. Yes constant circulation is more efficient: steady state VS roller coaster ride. What I do is mount the Comfortol in the largest heat loss are generally the great room. When doing so the comfortrol becomes an indoor sensor and constantly circulates that zone changing the supply temp according to your setting. Allow the rest of the zone to control themselves independent of the Vito.
The #20 controls your secondary system pump this comes with the bigger units and you will need to buy an expansion board for the smaller units.
Here is a Viessmann article explaining constant circ.
Good Luck Jeffrey

Simply Rad_2

Forgot something

Let the Vitodens control the secondary pump it will constant circ and will shut off in WWSD. Sensor is in the white box. Make sure to follow all the steps in the start and service guide: if you do she'll purr like a kitten and not roar like a lion. Take a visit to Viessmann Academy and get ready to expand your mind....
Jeffrey

Mike T., Swampeast MO

The heating curve is INTENDED to be adjusted by the user. Why? Because they're the ones living with the boiler--not the installer. The Vitodens gives the user COMPLETE control over both their comfort and their energy efficiency!

Unfortunately the instructions in the user manual regarding adjusting the heating curve are a bit lacking.

With high-mass emitters like floors where daily setback of room temperature is either slight or none, it's relatively easy to set the curve.

On initial setup set the curve shift to zero and the slope to the lowest recommended for your emitter type.

Set the sun dial at the MAXIMUM temp the occupant desires--try to talk them down from anything above 67F with radiant floors... If you've done your job you've slightly "over-tubed" bathrooms--perhaps even by heating some walls or ceilings in addition to the floors... Either disable daily SUPPLY TEMPERATURE setback by adjusting the default timer schedule or set the moon dial the same as the sun dial.

Then--seriously--have the customer set ALL thermostats HIGHER than the temp they want to maintain.

Then have them follow the instructions in the user manual for curve adjustment. STRESS that adjustments should be made in SMALL INCREMENTS with AT LEAST TWO DAYS between adjustments. (Any discomfort during the adjustment period will be repaid in both comfort and fuel economy later.)

As they find zones that tend to overheat relative to others, they should reduce the thermostat settings in those zones to their desired temperature.

Eventually, the situation will arrive where at least one zone (with the thermostat set high) is being reasonably maintained around their desired temp. This will produce the ideal efficiency for the system involved.

THEN to absolutely "home in" they can adjust the sun dial to match the space temp in the idealized zones(s). This will involve adjustment of curve shift ONLY!

S Ebels

What model

What model Vito are we talking about here? The two smaller ones (6-24 & 8-32) incorporate an onboard system circ and the two larger ones (11-44 & 15-60) require a field supplied circ.