Best Water Heating option for Vitodens 200

veissman_Bob

I'm in the process of specifying a Vitodens 200 heating system and need advice on my best DHW options.  I'm trying to decide between a tankless hot water system or an indirect tank (I'm nearly certain I'm going with the indirect unless you all have a good reason why I should consider tankless (or another option)).

For the indirect, I was considering either a Weil McLane or a Prestige Smart tank but my local plumbing supply house where I bought the Vitodens 200 tells me that the Lockinvar Squire tank is a better choice, supposedly because the temp sensor for that unit connects direcly and easily to the Vitodens.  They're telling me that the W/M and Prestige tanks will require some other type of controller or interface to connect to the Vitodens.  Any help anyone can provide is greatly appreciated!

CMadatMe

Wrong

You don't have to use a Viessmann Tank. The sensor will fit in others wells. May have to use something to keep it snug against the well if it fit loosely. I would be doing in the indirect not the tankless. Boiler control can also run a re-circ pump if their is one on the system. You inquired in another post about a Vitorol 300. You would have domestic control if you use it. There are alot of ways to control the indirect via the boiler control



You can still get 90% plus efficiencies on the boiler even making domestic hot water. What size boiler did you install? Also remember that the indirect should be piped on the boiler side of the low loss header so that the domestic pump, pumps through the return of the boiler and piped ahead of the boiler pump.

veissman_Bob

WB2B 17-45

Chris, I've got a Vitodens 200 WB2B 17-45.  It might be a little oversized as my heat loss calc for the house is about 110,000 for a 2300 sq ft, 2 floor 1960s colonial.  The heat loss didn't include another 1,000 sq ft heated walk out basement.  I've got good R30+ attic insulation and I'm going to add blow-in insulation in the walls shortly.  

I'm planing on getting a 60-70 indirect - might be a little larger than I need.  We have 3.5 baths (two standard tubs, one shower) and two teenage boys and one wife that likes long hot showers.   I just want to be sure I get a tank that can support four consecutive showers, two at a time, back to back. 

CMadatMe

Your Contractor

In the programming your contractor can limit the rate of modulation for the heating cirucit independent of the domestic. Just make sure that if you use someone other than Viessmanns tank  that you size the pump correctly. That pump has to be able to overcome the loss through the indirects coil plus the boiler head while being able to maintain the proper gpm through through the boiler.



I personally would do the Viessmann Tank. Has a larger coil then most indirects and will have no problem keeping up with a 50 gallon tank. Look at the 100 Series not the 300 Series. You'll fall down and knock yourself out when looking at the price of the 300 series.

veissman_Bob

You're right!

I've seen the price of the Vitocell 300 and it's absolutely nuts.  Viessmann said the 300 is the best, they also told me that I could get a resonable service life out of the 100 tank if I religiously changed the anode rod. 

CMadatMe

Will Last a Lifetime

If you plan on staying in the home for the rest of your life the 300 would be the tank. That stainless is the same as what is in your Vitodens.  Would be the last tank you would ever need to install. The 100 is still a nice tank and provided you do the preventative maintenace no different then any other tank it will provide you years of hot water. One hint. Order the link annode rod and put it in before you install it if height at service time could become an issue.

meplumber

Pay attention to circ sizing.

As Chris stated before pay attention to circ sizing.



Even with the 100 tank.  I have had 2 separate instances where the 100 tank was causing short cycling on the Vitodens.  I was within the published head loss of the circ but had to up size.  After doing so the short cycling went away.  I have never had that problem with the 300.



I agree.  The 300 is the last tank you will ever buy.  The 100 is a good tank.  Linked anode rod is necessary for the 79 gal tank if head room is even remotely tight.



Good Luck.