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Viessmann 200-19 pump question.

TAGTAG Member Posts: 213
Viessmann has the Grundfos 15-58 3 speed on it's list for the indirect water tank loading pump. It seems this is also fine for the system pump for LLH loop. I see some installed systems with the Alpha 15-55 pump -- I'm guessing for the lower electric cost. I can see the savings for the system side since it's running 1/2 the year ... but, the indirect pump is not going to run all that much. Are the alpha pumps reliable? The cost difference is not that much .. but I don't want to install a less reliable pump.

I guess the 15-42 is now obsolete ...?


  • Paul PolletsPaul Pollets Member Posts: 3,293
    No more 15-42. The Alpha pump works well on the system side and will save large amounts on electrical load. I use the 15-58 for indirects up to 53g and a larger pump for 80g or larger tanks. I use speed 3 for fastest recovery. There is a chart showing recovery rates for the indirects in the Viessmann literature.
  • TAGTAG Member Posts: 213
    Paul .. Thanks. It was some of your old posts that had me wondering what direction for the pumps. The Viessmann indirect chart was interesting -- the output/ recovery difference between the 42 and 53 tanks is so small.

    I'm still trying to understand what is best for the system side -- individual pumps or 1 smart pump and zone valves.
  • Paul PolletsPaul Pollets Member Posts: 3,293
    I like a dedicated pump for DHW recovery. I use a smart pump for system side with zone valves, if required, or prefer to zone individual loops with telestats if thermostats are requested. The continuous circulation of the system takes advantage of the varying flow rates of the smart pump and once the heating curve is dialed in, is extremely accurate in keeping the setpoint. The parasitic electric load of using multiple pumps (or "wall of pumps") needs to be considered in efficient system design.
  • SuperTechSuperTech Member Posts: 1,333
    I definitely prefer zone valves (Calleffi or Taco, not Honeywell) in combination with a Grundfos Alpha circulator or a Taco VR1816 for pumping the zones. For a primary/secondary setup I prefer to use the Taco VT2218 for the primary loop.
  • TAGTAG Member Posts: 213
    Will get the 3 speed for the DHW and the Alpha for the boiler LLH loop.

    Would really like to have the bulk of the system with continuous circulation. The main part of the house is Warmboard -- that would benefit from continuous. But, how does that work with two manifolds ? One will be in the mechanical room and one about 25' away ?

    The house will also have a zone (7 manifold) of plates (one room) -- and another area that's a slab w/ 8 loops. I would love to have one smart pump doing the Warmboard and have that pump ramp up and send flow to the other two manafolds when needed. Thinking of a zone valve controled by thermostat for the areas. I guess one delta P pump off the LLH

    Otherwise it's two more pumps with thermostats --- would not delta T work here?
  • TAGTAG Member Posts: 213
    I'm trying to finish a project from hell. This is a big rehab I started years ago that's been nothing but problems. We had to fire the main contractor ..... I have the proper sized Viessmann 200 boiler w/ many of parts from the previous subs. Unfortunately -- the sub that I like the best is not as familiar with Viessmann.

    This house is also going to have a zoned VS ducted system with propane furnace heat pump + some mini-splits. So there is a lot going on ....

    spring/fall .. the radiant may not be on -- as the temps drop it will be ...
  • Paul PolletsPaul Pollets Member Posts: 3,293
    Each type of radiant application has its own water temperature requirements. If the design calls for more than a 10 degree difference, then a separate mixed temperature is required. The control can handle more than one mixing valve. The system can do 2 temps with one 3 way mixing valve and motor kit. If you pipe the same temp to both the slab and Warmboard, you'll have balancing issues.
  • TAGTAG Member Posts: 213
    edited December 2019
    Thanks Paul ... My plan was to try and use one water temp. The large room with the extruded plates should be requiring about the same as the Warmboard. I was thinking of using a room thermostat w/ floor sensor for controlling space.

    My guess is the slab could use slightly less temp water .. But I was thinking of room thermostats w/ floor sensors here as well. The slab area is really two rooms w/ different loads (4 loops each of 1/2 PEX) .. so even with another mixing valve I have the need to two different outputs/ temperatures for the slab.

    My goal would be to run the Warmboard with ODR off the boiler. The upper most floor is the plates and even if I had gone to the expense of ripping out what's there and installing Warmboard -- it woods still need to have some type of High Limit to keep the space from overheating.

    I would like to do the same with the slab -- warm the floors and use controls as a high limit.

    Not sure what is the best control for this --?

    Here is the project -- I'm standing in the framed kitchen addition looking into the dinning room located in the stone building. You can see all the Warmboard .. that upper area in the rafters is the existing living room where the plates are going to go. all the levels are open to each other. the slab is under me in the kitchen and the dinning room.

    You have been a great help.
  • Paul PolletsPaul Pollets Member Posts: 3,293
    You don't mention if you put the project through design software (Uponor, Viega, LoopCad, etc). These programs give you exact data on water temp requirements, manifold balancing, pump flow requirements and overall heat loss. Guessing water temp requirements can be "iffy" and lead to problems down the road. I urge anyone in the business of hydronics to learn how to use the software and take all the guesswork out of the game.
  • TAGTAG Member Posts: 213
    Paul -- The direct answer is no. I really trying to understand the pumping limits with known zone loop numbers. Let me explain . Have had the buildings heat and cooling loads figured. In more than one way -- 4 that were done room by room.

    It's complex because the stone building now has 5 levels within what was the old church. I have owned the property for many years and the rebuild is the result of a fire -- so I have history with the buildings HVAC -- it was heated with two oil hot air units and oil DHW tank ...pre-fire.

    When it was determined that we needed to remove and totally rebuild the two story Kitchen addition off the back -- we figured heating the new slab was prudent since there is a big bathroom/ dressing room under the kitchen (on the slab). The project grew from there -- I figured warm floors would be nice throughout .. so in went the Warmboard subfloor when we pulled out most of the framing. Since we did all the Warmboard -- why not find some way to warm the final space as well -- so now the plates under the living room floor that we are keeping in place.

    Understand what you are saying about the software ... How I approached. We did 6" on center when we put in the slab PEX ... I made sure that the Warmboard can provide the needed BTU SF that each space requires ... same with the living room plates. The whole thing is spray foamed.

    Some of the loads are difficult to determine as each level is open to each other in some way. Warmboard does a layout -- based on how you want to set up your project. In my case I was able to zone each room staying within the guidelines of PEX length.

    Another factor is that since I need AC -- there is going to be a full ducted system in the stone building and mini splits in the addition. This includes a propane furnace ... the plan is to use both -- as the ducted is a 3 zone modulating system. So the floors will only be for warming in much of the building.
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