vitodens 200

Mike T., Swampeast MO

Another way you might get quicker recovery is with code address 028

It's factory set at 028:000 With that setting the maximum temp <I>differential between boiler and DHW setting</I> is contained at address 0A0 <B>(in degrees Celcius)</B>. The factory setting for 0A0:020 means that the max temp differential between the boiler and the DHW setting is 20°C (36°F).

Address 0A0 can be set for up to a 50°C (90°F) differential.

OR if you set address 028:001 the boiler temp is only limited by the limit thermostat. 172°F (78°C) With 028:001 the value at address 0A0 has no effect.

The higher supply temp during DHW production (provided you're at factory settings) could help your recovery rate significantly.

Mark_7

vitodens 200

Talked to our salesman the other day and he said we can only install th 200's with a viessmann indirect tank or phase III tank. Because there finding other brands don't have enough flow though the heat exchangers and the unit short cycles. Anybody having that problem?

joel_19

Vitodens

Well Viessmann makes the best indirect so if you can sell it than you might as well. That being said we have sold something like 10 ? of them with the Crown Indirects without any problem over the last 18 months or so. We don't do much gas mostly oil here so I haven't had the opertunity to sell too many of them.

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Paul Pollets

Flow rate for DHWT coils

Make sure your DHWT coil is piped 1" (always) from the boiler. Even though the stubouts are 3/4" on the Vitodens, increased pipe sizing to 1" is required.

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Mark_7

vitodens 200

What size units? He said the 6-24 works ok with the crown tanks but 8-32 and largeer there having problem with.the job I'm doing has a amtrol which has to much coil restriction anyway.

ALH_3

Crown Tanks

The Vitodens boilers work great with Crown tanks. The 79g has more noticeably more pressure drop across the coil than the 40, 53, or 119. As mentioned already, keep the piping 1" on the 6-24 and 8-32 Vitodens, and 1 1/4" on the 11-44 and 15-60. The large Vitodens requires a high head pump (on the order of a 26-64 or 26-99 depending on application). The Crown tanks are excellent and work incredibly well if piped and pumped correctly.

-Andrew

heatboy

If you buy a Vitodens........

you buy the 300 indirect. No option.

ALH_3

?

Is that an "if you can afford a Vitodens, you can afford the 300" statement? Have you had any customers back off because of that insistence? I'm just curious. I wouldn't mind seeing a Vitocell 300 in every home.

Have you had any problems with Crown tanks?

-Andrew

Weezbo

This is always of interest to me...*~/:)...Thanks for the input

HeatBoy And Paul...Increasing pipe size and using a pump vs a zone valve and a dash of prioritization sounds like a good idea*~/:)

Paul Pollets

Pump included

Weez, the Vito has a built-in "smart" pump up to the 8/32 model; the pump does the DHW and the radiant load. No need for a ZV or pump., Not an option.

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Mark_7

vitodens 200

Is the vitodens worth the price over the cheaper priced gb142 buderus. viessmann seams to do a lot more for the contractor in service and training wise. Any thoughts.

ALH_3

Value

I think the Vitodens boilers are a good value. There is a lot of versatility in the controls. The heat exchanger and burner are second to none. It's the best modulating, condensing boiler on the market. My only complaint is the need for so many adapters to get to NPT.

That doesn't mean that the Buderus isn't a good value. I haven't worked with one, so I can't really comment.

-Andrew

Unknown

I'll be watching this thread

One job I did last fall had an old HTP SSU 45. I connected straight onto a WB2 8 32 and he's been unhappy with the recovery rate since I put it in.

Thought it might be scale/lime etc. Tried selling the V 300 but he all ready owned the old SSU.

Any thoughts as there is no clean-out door on HTP's SSU.

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Constantin

Well, you could try the following:

There are small fiber-optic cameras sold to look into wall cavities and other hard-to-reach areas. Simply drain the WH, unscrew the drain, and have a look. Scale should be present primarily on the HX coils, though if a lot of scale comes out via the drain cock it's probably time to call George at Rhomar or to concoct your own white-vinegar/muric acid/etc. de-scaling cocktail.

ALH_3

Coil Design

I'd blame it at least partially on the poor coil design of the Superstor. Jamming the entire coil in the bottom of the tank isn't very conducive to high recovery rates.

-Andrew

heatboy

Not at all, Andrew.

I sell the Vitodens as a system. Since the Vitodens is the best boiler we have available to us, it makes little sense to "cheapen" the project by substituting a sub-standard indirect. Domestic hot water makes up 30% +- of energy consumption. The Crown, while being a wonderful budget tank, is not really compatible with the performance you can achieve with a Vitodens. The tiny HX and needed high boiler temps for recovery don't make for a good match with this boiler. We have many Mega Stor indirects and they work well, when used in the right scenerio.

The Vitodens is a great machine when all other components can perform as well. The only indirect on the market that should be used with it is the 300.

ScottMP

sizing the tank

properly and correct piping practices are ussaly the culprits for poor recovery.

I install SuperStor tanks all the time and have no complaints when sized correctly.

The Viessmann tank is a superior product

Scott

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ALH_3

Agreed

I tend to agree. However, to be fair, the Mega Stor tank is the next best thing, and will work quite well with Vitodens boilers. I haven't seen Vitodens boilers "short cycle" with Crown tanks.

-Andrew

Paul Pollets

RPM

Gary, did you turn up the RPM on the pump in DHW mode? The pump comes factory set at 65%. turn it up to 95% and you'll see a difference, providing the piping is 1" to the coil, and there's no scale in the system.

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heatboy

Not having used.......

a Mega Stor with the Vitodens, I can't say how good it would perform, Andrew. Although, check the performance curves of both tanks and you will notice a huge difference in recovery capabilities, pressure drops and GPM requirements.

The next time you are at one of the Mega Stor projects, set domestic water temps on the Comfortrol up 5° higher than current setpoint and watch it run. Measure your Delta T across the HX and pay attention as it approaches the new setpoint. If the boiler is going to cycle, it'll do it then.

hb

Unknown

Paul,

Thanks for responding to this thread.

I'm assuming that you are referring to coding address OA9 (Max. rotational speed of circulating pump for DHW production).

The unit is set at the factory default of OA9: 098. It's not clear to me as to what % the (possible changes) coding values represent. Value 001 through value 100 are the possible changes. If 098 is the factory default, this means that the pump runs at 98% of the rotational speed and not 65% as you describe. Am I missing something here?

Thanks for your input.

BTW, I sold my first V 300 today:-) Wish I could sell them on every Vitodens job I do but, the price point is hard to overcome for most of our consumers. While the HTP SSU is less money, in terms of design it falls well short of the benchmark of big V's IMHO.

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Dave Jahnke

0A9:095

I believe the coding address is 0A9 that needs to be changed. James Brown at Viessmann would know for sure.

Paul Pollets

Gary...

I'd call James Brown and go through the codes. Typically, the DHW pump is preset at 65% rotation...I'm not sure why. Recovery rates in tanks other than Viessmann's have sometimes posed a problem.

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Unknown

Nope.

This address has nothing to do with DHW production.

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heatboy

Don't want to be the bearer.......

of bad news, Gary, but there is no coding fix for your situation. The combination won't work. Just check the pump curve for the internal pump to prove it. Won't work. Your option is to connect the indirect downstream of the LLH and use the external heat demand circuit. That way you can size a pump that will do the job.

I have done jobs without the Vitodens because I will not sell anything but the 300 with it. Sell it as a system or don't sell it. But I think you already know that. If you sell it as a system and there are issues, it's Viessmann's cash that will fix it. Otherwise.......

joel_19

heatboy

Very Gutsy Move I haven't tried that take it or leave it. I like it , kind of like "lifes to short for cheap beer...". Haven't expierenced those problems yet on the Crown though. I've had a tuff time upselling the 300 tank , my own failures as a sales guy come through again. Like the 04 Sox you just gotta believe...

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ALH_3

I'll give it a try.

I'll also try it on a 300 project.

I certainly won't argue that the Vitocell 300 is a superior tank.

-Andrew

heatboy

Thanks, Joel, but.......

not gutsy at all. I love the Vitodens and I am pretty sure there is nothing else like it. But, it's just a boiler. I have Vitolas, Vitogas, Freeports, Cabos that I can offer. I won't compromise the performance of the Vitodens to fit someone's real or imaginary budget. Period. Once you distance yourself from the project, it's easier to sleep. I make as much money on a Freeport as I do a Vitodens. Which boiler I install really doesn't matter as long as the money is there.

hb

You're right. Joel. "Life is too short to drink cheap beer!" I love that.

Paul Pollets

Jeff...

Why would an 8/32 have such a difficult time recovering a 45g indirect, supposing 1" S/R to tank coil??

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Mad Dog_2

I like that approach too

Keeps ya outta trouble. Mad Dog

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Mad Dog_2

I agree Scott I also

really grill the user about "what they expect." How much how long. If there is any doubt I bump up to the next size. Mad Dog

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heatboy

Pressure Drop and .............

required GPM, Paul. The internal pump can't pump the indirect plus the boiler at the GPM required for recovery (not designed to). And since it can't, the boiler will not run at high fire with reduced flow through the boiler HX, further reducing recovery abilities.

Like I said, I haven't used a Mega Stor with these, but I sense it would do the same thing due to the larger drop through the coil. With low flow the boiler automatically modulates down to try and match the lack of flow. So an 8-32 may actually be an 8-20 or worse.

Remember, the publish recovery rates on most indirects are set around 180° boiler temps. Not happening with a Vitodens.

Bob Knebel

Vitodens 200 Technical Data Manual

Great discussion everyone! Thanks Heatboy!

For those interested in the Vitodens boiler, you may want to download the pdf file "Technical Data Manual" from the Viessmann site:

http://www.viessmann-us.com/web/canada/ca_publish.nsf/Content/Vitodens200_ca_english

Sorry I dont' know how to make this a "hot link."

Page 9 gives a graph of "residual head pressure of the built-in variable speed pump" for the two smaller boilers 6-24 and 8-32. I will try to attach it here.

If one changes the speed to 100% (2700 rpm) through the proper coding address, it is possible to get an "extra" capability of the on-board pump to drive a good "ported-out" high performance indirect water heater such as Viessmann, Crown, Phase 3, etc.

We have even designed our radiant floor or panel rad systems for very low pressure drop so that we could use only the on-board pump to drive both the space and water heating systems.

However, to do this, careful design and selection of components are mandatory. No doubt the Viessmann tank is the king of heat exchanger surface area and low pressure drop but we have also had good success with the Crown tanks. Using the attached graph and the flow information for the Vitodens 6-24, we find that for a 30° temperature rise across the boiler at 5.4 gpm flow, there is a residual head pressure of about 3 ft left to run a water heater. A Crown MS-53 tank has a coil pressure drop of 2 ft at 5.4 gpm.

I definitely concur with Heatboy and wouldn't try this approach with some of the indirect water heaters on the market.

Bob Knebel ...... Radiant Engineering

Mike T., Swampeast MO

Bob,

Is it not also possible (with tanks of less generous HX area) to speed recovery by manipulating the differential temp as mentioned above? Heqq--you can even make a fixed supply temp--not quite 180° (172°) but provided reasonable reserve flow ability, surely heat will transfer rapidly enough to keep the burner modulating and prevent it from "bouncing" around the high limit.