Vitodens w Staple-Up-PGP

Tom Hopkins

paul where is your curve? and whats the house like?

Paul Pollets

Vitodens du jour

This project is common to the powerfrul radiant renovation market in Seattle...remove the existing furnace and install a Vitodens with Staple-up radiant (with transfer plates, of course) 50% of the new clients choose to use the B300 solar tank with dual coils. Many are waiting for more favorable tax credits before installing the rooftop array. We piped the system for a future wall panel radiator zone in the basement.

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Todd Schliphack_2

Install

Great job as always! The attention to detail with the pipe supports is impressive and looks time consuming for a residential job.
Very Nice

scott markle_2

nice work!

I like the LWCO location, do you have any close ups on that? who makes those nice stand off connections?

I'm having an a vito issue in my own home (single zone radiant .5 curve. ) and was hoping you might have some advice. My issue is that the boiler seems incapable of producing supply temperatures below 100f without what I feel is short cycling (10-30 sec. burns)

The structure has a heat-loss pretty close to the low end output of the vito (22,000). I have set the burner limiting potentiometer to it's lowest setting and have never observed a heating deficiency. I started with a low loss header based on a reps. recommendations, but became suspicious of the need for this and removed this fall to see if it was effecting this short cycle issue and because I was interested in saving some electricity on (in my view) unnecessary P/S pumping.

It's my opinion based on observation and experimentation that the boiler is not capable of producing supply temps below 100f without short burns. The low heat loss would seem to be the problem and much has been made of the use of buffer tanks to cope with this. However I'm fairly certain this is not the problem.

The vito 200 lights on high fire and modulates down , my observation is that it takes about 30 sec. to reach low fire. In this 30 sec I have no appreciable rise in my return temperatures yet invariably at target temps below 100f the burner shuts off before minimum modulation is sustained for any significant length of time.

I have experimented with pump speeds and I'm confident my flow rates thru the hx are adequate, If I adjust the shift (sun) dial upwards to trigger a supply temp above 100, no problem. I get nice sustained burns.

I was actually considering using the boiler disable/ contact to operate the boiler in an on/off fashion at a fixed 110 deg temp by means of a interval based outdoor reset control like a tekmar steam control. Unfortunately this is a very expensive control ($1000) so this is not a viable experimentation option. Perhaps operating the boiler at a minimum supply temp (100) and using a motorized mix valve is another option, although this would also be expensive and require a additional energy using circ.

What is your experience with this? are you comfortable with the short burns that seem inevitable in low temp apps. using this boiler?

hot_rod

Nice clean work

even unfired water tanks need seismic straps?

hot rod

Paul Pollets

EQ restraints

Yep. Even the expansion tanks need strapping in this EQ zone.

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Paul Pollets

Scott...

The hangers are available from ARGCO.com.We make the LWCO connections with brass fittings.

The Vitodens has a short burn cycle on the low end. Since the pump is continuously running below WWSD, it's never a problem. I wouldn't use the boiler disable circuit...it's for high temp overide, like when a snowmelt or AHU HW coil is connected. The LLH needs to be installed when designed flow rates exceed 7gpm. Otherwise the internal pump will work independently as long as it's the only circuit.

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Keith_8

Clean

Well thought out.

Keith

hot_rod

Do you use both indirect coils

connected to the boiler until the solar gets added? it's a good way to lower the return temperature to the boiler on DHW calls.

hr

Paul Pollets

That's a good idea!

...to use both coils. This house is a 1800SF bungalow. Only 2 people live in the home, so DHW load isn't large.

The Vitodens 200 fires at 167 on DHW production. 1.4 slope. I'm not sure the recovery would be any faster using the integral pump, even with 2 coils. The rooftop array will be installed in April. I've one client that we're keeping the tank at 140 and tempering at 120 foa added capacity untill the array is installed. The Euro's prefer 140 as the tank temp to kill any Legionella.

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Mike T., Swampeast MO

Exactly the operation I observe with my Vitodens when loss is low. The "pulsing" [seems] to be intended operation and efficiency does not appear to suffer.

[Deleted User]

Impeccable...

as usual.

You should charge more and get paid for it.

ME

Paul Pollets

Thanks, Mark....

Our pricing is typically the highest in the Seattle market. Then again, we're the only contractor specifying Viessmann. Like any other marketplace, there is often a 50%-100% spread (by "Others") on any project bid. All the better to confuse the customer.

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scott markle_2

normal pulsing

Thats pretty much what Viessmann says. The most assuring explanation from them is that the boiler was designed for instantaneous DHW production (combi) and as such was designed to tolerate cycling.

Ultimately I don't care if the unit can handle this, I don't like it. I don't believe it's terribly efficient either. How can a series of short burns (some less than 10 sec.) be as effective as an equivalent longer burn? A flame takes time to stabilize and the initial ignition leaves some fuel unburned.

I'm using the tekmar 269 steam control. via the demand for heat contact. My sun moon dials are set to 0 and the programed external demand temp is set to 117 (in operation the longest burns are only able to reach about 113) The blue burner output potentiometer (back of main board) is set to it's lowest position, I'm using a 35min cycle length on the Tekmar. The actual burns are calculated as a percentage of this 35min. cycle. On the low end these cycles are 2 min. every 33min. control is adjusted such that continuous operation is at -30 outdoor.

The 269 has been in place for 2 months. I'm very pleased, I have not noticed any diminishment of comfort. Very high sustained delta T (30+). I'm expecting some formal feedback from Viessmann engineering on this soon.

As housing becomes increasingly efficient (low load) It's my feeling that a there is a real need for smaller mod-cons. The only obstacle I see is how to meet dhw loads with a smaller boiler. Personally I would be willing to give up the endless shower, supplemental solar could help in this regard.

Looks like the vito-200 we know is pretty much obsolete across the pond. I notice that many of the euro models have a lower end output. I would love to see a 343-f in N.A Euro Vito brochure attached.

[Deleted User]

Vitowow

Lambda combustion control.

An answer to synthetic fuels in natural gas...

Looks like quite the unit. Looks like Iman's been busy!

ME

Tim_41

This is close to what I am doing to my own house. Thanks for the pictures. I hope to have the solar running sometime this spring. I need to paint the CI rads and get the rest of the flooring down. Did you use a spirovent with the LLH?? Nice work.