Vitotronic Controls

Brad Barbeau

I'm wondering if anyone has experience using the Viessmann Vitotronic 200/300 in multiple zone applications. Their literature says they can be used "for heating systems with one heating circuit without mixing valve and up to two heating circuits with mixing valves."



Perhaps I'm missing something (I'm a homeowner) but what if I wanted to use two circuits without mixing? Or is that something I don't want to do. I will be all cast iron rads and from what I know mixing isn't necessary - or have I misunderstood. I'd like to have at least two zones, perhaps even three but if I'm going to use the Vitronic controls, does it somewhat defeat the purpose to then have to add other relays to achieve high temp zoning?



I did wonder that if the boiler is being used for DHW that the mixing valves will stop hot(er) water from heading to the rads on a simultaneous call for heat and DHW.



Thanks for any comments - curious what those who have installed these controls think of them too.

R.Bell

Vitoronic Controls

I have a Vitotronic 200 high temp circuit feeds Runtal rads, mixing valve circuit feeds the in-floor heating, I am very happy with the Vitotronic unit have had it installed for about 5 years now and it works very well - multiple programming combinations and adjustments.

In your case I would if I did it over again use mixing valves even for the high temp circuit as this gives you a much tighter control of the temp level in your home as well as using less energy and offers protection for your boiler - not sure what type of boiler you have.

For DHW you can program the control to give priority to DHW production this means the heating circuits are shut off till DHW production has been satisifed.

Have you contacted Viessmann as well with your question?

You can download the Vitotronic Manual from the Viessmann website and study it in close detail to see what the various programming options are.

Hope this helps!



 

Brad Barbeau

Nice!

Glad that you like it. I'm thinking of going with the Vitola but I haven't seen the price yet...that may change things.



I have looked at their documents but it didn't look like two high temps were possible. But given what you said about mixing even with the high temps, that solves the problem - just mix and I've got two zones that are even more efficient.

R.Bell

Vitotronic Controls

I have 2 Vitolas one is gas fired the other is oil fired at a remote location.

Can highly recommend the Vitola boilers make sure you get a good installer to put it in if that is the way you desire to go.

Otherwise the Vitodens wall hungs are also a very good way to go - depends on your budget

Would also highly  recommend the Vitotrol 300 wall thermostats.

Paul Pollets

Viessmann controls

If you have cast iron radiators, using a 4 way mixing valve prevents thermal shock on the return. You can choose not to install the mixing valve, but should consider a system bypass or boiler bypass to make sure return water is above 130. The Vitotronic 300 can handle 2 mixed temps (using mixing valves) and 1 high temp circuit. The Vitotronic 200 can handle 1 mixed temp and 1 high temp circuit. Both controls will control a DHW indirect tank.

Brad Barbeau

Vitodens or Vitola?

Given that propane is more expensive than oil per BTU here would you go with a Vitodens or the Vitola (we've got oil currently)?

Paul Pollets

That depends...

if you have a truly condensing load, the Vitodens would be my choice, but the Vitola is less expensive than the Vitodens and oil has a much higher calorific value than propane. I'd lean towards the oil appliance.

heatboy

I'm not sure it is.......

Here in lovely eastern PA, propane is around $2.40 PG and #2 is $3 PG.  It makes the decision, provided you can condense, which fuel to choose easier.

Brad Barbeau

That's good to know

My load is actually not ideal for condensing (unless I'm wrong), all cast iron although I did size the rads for about 155 degrees. 

I didn't realize the Vitodens was more expensive so that's good too. 

CMadatMe

A Heating Circuit

Is not a zone. In the Viessmann world a heating circuit is a circuit that needs a different water temperature then the other. For instance, you have baseboard heat and some radiant. Heating Circuit 1 would be the baseboard which requires hotter water and would run off the boiler curve. Heating Circuit 2 would be the radiant being controlled by a Viessmann Motorized Mixing Valve because you need a cooler water temp then what is being delivered to the baseboard. You can have as many zones as you want within each heating circuit.



They also make another mixing valve that can give you a third heating curve if necessary. Heating circuits are the orchresta. The boiler control is the conducter that directs what to do by the sheet music you input into the control.



If this is a gas job I wouldn't do a Vitola I would do the Vitodens. The Vitodens is more efficient based on AFUE and with the added controls the Vitola may end up costing you more. The Vitola before the condensing wall hungs was the workhorse for us on gas but since the introduction of the new Vitodens 100 and 200 with the price coming down 25-30% over the previous Vitodens family you will find its the better investment.



You have cast iron which is a condensing boilers dream. Even at 155 for your design day your can get in the 90% efficiency range for Vitodens. Would have to compare the heat loss to the boiler output. May be able to limit modulation rate. 



There are also other things we can do to limit that water temp like indoor reset via Vitotrols that work in conjunction with the outdoor sensor and provide feedback to the control. So the boiler looks at indoor temp/outdoor temp in the calculation of the curve.



I would take a look a good look at the comparisons for Vitola and Vitodens and the application before making a decision. I would also make sure I'm dealing with a contractor that has plenty of experience with the product line.

Brad Barbeau

That's helpful too!

After reading your comments, it got me thinking that perhaps we should step back from the fuel situation and find the best (most efficient?) heating plant for our situation and then deal with the fuel afterwards. So we've got a meeting setup with the contractor and the sales rep from a large mechanical & engineering company tomorrow to find just that.



Here's a question though about the Vitodens: it looks like the WB2 11-44 model will only modulate down to 49 MBH whereas a similar Ultra 3 and the Knight will go down to ~29 MBH. I'm heating two buildings with this, the house and an attached coach house. Loss on the house is ~85 MBH and coach is ~45 MBH but in the shoulder seasons I wouldn't necessarily be heating the coach house, not until we get closer to freezing perhaps. So the lower limit of 50 on the Vitodens seems like it would be a bit high. Or am I totally wrong on that?



Of course I suspect that situation is even worse with oil because we'd be firing at the higher rate the entire year when it would be grossly oversized much of the time.



Thanks!

Brad

CMadatMe

That's the Old Boiler

Your looking at the old Vitodens 200 boiler the WB2A you need to look at the WB2B Series which is the current model. A WB2B-35 is the model you want to look at 31,000-125,000. Does that coah house have some form of supplemental heat and you need muscle on the colder days? If so, you don't need to overcome the entire loss of the coach house just need enough btu's to get you to setpoint. Can figure that out utilizing the heat loss. Change the outdoor temp to what the room temp is at the time you need the boiler to come on and that will tell you how many btu's you need to get to setpoint. If no heat exisiting and your just looking to keep the place from freezing then drop setpoint in the heat loss to what temp you want and recalculate the loss.



I would use heating circuit one for the coach house. Have the boiler come on only when necessary via a Vitotrol. The boiler will calculate it's curve not only based on outdoor but the coach houses indoor temp. Heating curcuit 2 would be a mixing valve for the cast on a separate curve.



You could also utilize the external demand feature for the coach house. You can maintain a water temp max and min when external demand calls. 



There are many things that can be done. All at this stage of the game so ask for as many options as you can. With this boiler you are not stuck in doing something one way.



 

Brad Barbeau

Coach house

There's currently electric baseboard in the coach house but that is coming out. The heat loss was done using an indoor design temp of 50 for that building. If I want it warmer I expect that most of the time the system will have no trouble doing that, just not on a design day (one day this week it was -22 F which is actually below the design temp I think!).



Would the 35 be big enough though? Max output is 114 and my load is 130?

CMadatMe

Would Have to See the Job

There's plenty of fudge factor in heat loss programs.You have an occupied and unoccupied space. The heat loss for the occupied space isn't taken into account, lighting, appliances, how zone setpoints are set, people, solar gain, how the rooms are layed out and open to each other etc.





If you asking me just based off a number then I would go up a size. I also don't use other peoples heat losses and would re-calculate myself and then make my decision based on the loss and job site visit. Have to calculate that existing radiation capability. You stated previously that 155 degree water would be enough so maybe I just boost my curve to overcome design day. There are also a few other tricks in the coding that I can play with.



 We are dealing with two different structures not multiple zones. My key concern would be the boiler is sized enough to heat the occuppied home now I just need to keep the unoccupied coach house between 45-50 degrees. That's why external demand may be the best way to control that coach house.

Brad Barbeau

Very interesting!

It's really too bad you're in New York and not Ontario...! We need more people like you here.



I like your way of thinking about that, sizing for the house first. I'm not even going to put the coach house on the system for a while so things may change. Personally, I think the load they calculated for it is too high given that I have only had heat on in the bathroom and just barely, but even then a water bottle I have had sitting on a table on the lower level has never had any ice on it. What the heat loss on a 160 year old house and what actually happens could be very different things I think. I do plan to add DHW at some point too.



I've been looking on the wall and trying to find the differences between the old Vitodens 200 and the new. I believe they are both available here (Canada) now - the A version has the matrix burner doesn't it? If both are available, am I to assume that the new version is better?



Thanks for all your help HVHEHCCA!



Brad

CMadatMe

New Version

Hands down the new version is better. It's also about 25% less. They no longer are using the dome burner. They found that they experienced hot spots at the back of the heat exchanger so they changed the burner. The new boiler no longer has a pump inside, no pressure switch and now shouts Lamda Pro Combustion. The boiler operatates the gas valve independent of air allowing the boiler to basically conduct its own combustion test on every fire. They have also changed the max water temp from the 165 to 176.



It's much cleaner and easier to service plus better venting distances and options. It's a much better investment. I attached some reading for you.