Viessmann WB2B Hot Water Priority?

Viess

I'm having a Viessmann WB2B gas boiler installed. It has a outdoor/indoor temperature rest. There will be 3 hot water baseboard heating zones and an indirect Boilermate DHW heater. The installer said that the priority hot water feature will not work with this setup. Something to do with the return water temp and the outdoor temp set point. I'm not sure what he is talking about. Any thoughts? The average winter temp is 0 degrees F. 

CMadatMe

Simply Wrong

That boiler is capable out of the box to do both. I'm going to assume by the WB2B that this is the new Vitodens 200 boiler. With this boiler he must purchase a seperate domestic sensor that is a accessory. Attached please see the tech data manual for the Vitodens 200 Boilers. There is a section for domestic water.



I don't understand what return water would have anything to do with this. The boiler is going to shut down the heat side and high fire to satisfy the domestic. The control on this boiler is capable of running 2 different heating temperature curves along with domestic out of the box.

Is he using the recommended low loss header and temperature sensor that goes in the low loss header to provide water temp supply feedback to the boiler? It sounds from your post that he is using either a Vitrol 200 or Vitorol 300 remote control sO I don't understand his logic concerning the domestic tank.

I would strongly urge you to educate yourself on this boiler.

Viess

Viessmann.

Chris,

Thanks for the reply. The boiler (Viesmann Vitodens 200 WB2B-35)came with a Type 80/50 17.6 GPM Low loss Header, a Low loss Header temp sensor and a DHW temp sensor. So I don't get it either. The Boilermate has an aquastat manual turn knob to control the zone valve that controls the water temp. So I was wondering if the DHW temp sensor from Viessmann will work with the Boilermate? It's just a temp sensor that needs a dry-well to operate, right? From there the boiler control will turn the circulation pump on and off as needed, right? Any thoughts. The installer just wants to zone valve the DHW tank?

CMadatMe

There Lies the Problem

You will not find even a mention of a zone valve in the installation maual. The Germans believe in pumps not zone valves.  He should be  zoning with pumps. See page 31 of the installation manual attached for a basic system layout. I also attached the other manuals so you can get a head start and educate yourself.

If this is an Amtrol Boilermate he has to remove the exisiting aquastat and probe and insert the Viessmann DHW sensor in the well. He can then pack the sensor with some insulation on one side to get the sensor to make contact with the side of the existing well to get the best readings. Has been done and will work.

Viess

Amtrol Boilermate WH-7Z 41 Gallon

Thanks again Chris. I have been reading the online manuals for awhile now. I get most of it. I started looking around and researching gas condensing boilers over a year ago. I decided to go with Viessmann because of their reputation and the Stainless Titanium alloy heat exchanger. Those aluminum mono block exchangers are crap and I steered clear of them. I spoke with the local Viessmann rep about the boilermate working with  my unit and he said well I think so/maybe. It's a relatively new water heater so I didn't want to through a perfectly good heater away. I'm glad to hear it can be made to work. Now I have to convince the installer it will work.  Thanks again.

Paul Pollets

Amtrol Indirects

I'm not a big fan of the Amtrol indirects, as they have had high failure rates and the coil is small. I prrefer either the Viessmann VitoCell tanks or the Triangle Tube Smart series as an alternate.

Mark Eatherton

Unless something has been significantly changed on the Amtrol...

Last time I tried t put a solid state sensor into an Amtrol well, I failed, because it is too small to receive anything but a bare thermistor. IIRC, they used a 3/8" ID well, and most sensors are 3/8" OD or greater, which creates a problem.



I hate to say it, but I'd suggest you get another storage tank. Look at Ergomax or Thermomax reverse indirect DHW heaters, then follow Viessmanns recommendations.



ME

Viess

Sensor Ohms?

Deleted

Viess

Sensor Ohms?

What does the resistance of the Viessmann DHW sensor have to do with

whether or not it will work with the Amtrol Boilermate? If you have to

pull the old Amtrol aquastat and probe and then insert the Veissmann

sensor. Why would it matter if it's a 15,000 or 10,000 ohm sensor?

That's what I'm hearing from the installer. Any thoughts?

CMadatMe

Viessmann Indirect

If the contractor is so concerned about the sensor and you want a indirect tank and no issues then the best way to go is to use Viessmans CVA or EVI tank. The CVA will be less expensive than the Stainless EVI but it will cost you more than and Amtrol.

heatboy_30

I would worry......

..... that the installer doesn't know the difference between a 10K and 15K sensor, neither of which Viessmann use.

CMadatMe

Didn't want

to get into that but your right..Thought maybe the easiest way to overcome the objection was advise the guy to use Viessmanns Indirect that way his contractor would have no issues to speak of.  I'm with you on the comment.

Viess

DHW

Yep you guys are right. Go with Viessmann DHW heater, problem solved. Thanks for the advise I appreciate it. 

Mark Eatherton

Or......

Go with an Ergomax or Thermomax, which accepts a large well and keep the boiler in condensing mode ALL the time...



Think outside the cylinder :-)



ME

Techman

Priority

Could it simply be the mechanic got the Vitodens 100 and 200 mixed up?

CMadatMe

New 100

The new 100 has priorty logic in the control. You just don't use a sensor. Has a sperate DHW block that you need to wire to. When that block is activated it shuts down RT (TT) terminals and goes into high fire.