Vitodens 200 Low Water Cut-Off Location

S Ebels

The two larger sizes also come with a built in flow switch mounted right on the "header" coming off the HX. The inspectors around here will allow that instead of a LWCO.

Thinking about it, I would choose the pressure switch as the optimum safety for residential use. A LWCO that's in a flooded condition can still be sitting under an empty system allowing the boiler to fire and the pumps to run even if there's no flow. A bad thing for small, low mass boilers. LWCO's are best suited for their originally designed purpose and that is protecting a steam system.

Perry_2

Hot ! Vitodens 200 Low Water Cut-Off Location

A question the boiler installers have: Where is the best location to install the low water cutoff when doing a Vitodens 200 with Low Loss Header install.

Can they install it on the secondary system - higher than the boiler? That would be the easiest place. - or should they install in between the LLH and the boiler?

They are on lunch break. Any fast answer would help.

Thanks,

Perry

ALH_4

lwco

See page 42 in the installation instructions.

The LWCO should be in the boiler loop.

-Andrew

Perry_2

Thanks

Thanks Andrew:

Both the lead installer and myself remember seeing it in the liturature - but could not seem to find it at the moment.


Perry

Steve Ebels_3

Always puzzled me

The code book says no valves between the boiler and the LWCO, yet the Vitodens comes with from the factory with iso valves attached directly to the boiler. Never had an inspector question it.

Perry_2

Turns out that

the Vitodens factory supplied Low Water Cut Off fitting (which we didn't have) connects directly to the boiler vent on the coil. Thus, if you have that - there would be no valve between it and the boiler.

Perry

Brad White_131

Funny thing

I came upon the same thought today, Steve. No valves between according to the literature either. But at least the LWCO is stated to be on the same circuit as the disconnect.

BTW: I downloaded the Canadian instructions posted above. Much more detailed than the US version, especially regarding fittings. More information overall including the LWCO location.

Perry_2

Another funny thing - use of UPS's and Vitodens

Several people have discussed the possibility of using a Uninteruptable Power Supply (UPS) on their Vitodens - and other mod/cons.

Most of these boiler plug into a recepticle...

Since the Low Water Cut Out(LWCO) is cutting power to the receptical... A LWCO would become ineffective if the boiler is plugged into the UPS and the UPS is plugged into the recepticle - which would be the normal way of connecting the UPS.

To make this work the LWCO would have to be wired after the UPS. While I am sure that their are ways to do that - It does create quite an ususual situation if you wanted to use a UPS.

Perry

Brad White_131

I think you just sold me

on that, not using a UPS, Perry. It would seem to defeat it. Naturally what I really need and want is power conditioning (Which my APC does really well, very clean power) but not at the cost of defeating a primary safety.

Good call.

Brad

Perry_2

To really protect your electronics install one of these

Here is a surge protector that works a lot better than the realitively cheap ones you buy in the stores:

www.brickwall.com

I have installed the "20 amp Panel Mount Unit" on the right side of the boiler (powering the recepticle W/ Switch) on the left side of the boiler where the Vitodens power supply hangs.

We have ordered the Vitodens LWCO connector and will mount it on the top of the boiler where it protects the boiler coil from air binding; and then wire it into the surge protector box.

Perry

When

Brad White_9

Great tip, Perry, Thanks

My existing circuit is a 15A and this needs a 20. What did you find the Vitodens actual Amp draw to be? Is your 20 overkill? Might their lesser products do? Nice line by the way.

The Vito installation information I have is thin and sporadic from on-line sources. Apparently did not get the packet of information with the boiler and accessories, just the accessory sheets that came with each. The Canadian literature as I posted really beats the US version, both on-line for the same unit.

My secondary circulator is on a separate circuit as is my DHW circulator (boosting to a SuperStor), so only the Vitodens is on the dedicated red-plate circuit with a CO detector and LWCO in series.

Sounds like yours is coming along nicely! I should get our lift off next week sometime. Boiler is hung, outboard piping all but done, hydronic board with LLH getting up this weekend...

Paul Pollets

LWCO on Vitodens

We were able to persuade the Seattle Boiler Dept. that the Vitodens has redundant safety devices and will not operate under 8psi or even turn on, when the coil is dry, and immediately faults. The fault switch is the "manual reset". The pressure switch will also prevent operation in the event of vent blockage.

They agreed, and we no longer have to put the devices on these boilers in the city.

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Perry_2

Surge Protector circuit sizing.

This is designed to handle a 20 amp circiut; and will handle any lessor load.

You can connect it to a 15 amp circuit. It will work just fine.

I did wire my boiler supply circuit at 20 amps - for other reasons that might come up in the future.

Perry

Man with a question

LWCO with Vitodens?

The Vitodens won't fire if water pressure drops below 9PSI. In essence, it has one built in. Why use a LWCO?

Thanks,

Happy_Jake

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Brad White_9

Codes, local AHJ's

and Viessmann's own recommendation.

I agree, it is "belt and suspenders" but cheap insurance just the same. As Paul Pollets posted, Seattle has allowed a waiver. Every jurisdiction may have it's own requirements.