Whole home viessmann boiler

Mn1985

Having new boiler installed in MN. Help deciding what to do

house is 4500 square feet with about 800 square foot insulated garage. Has radiant in garage, entire main floor, two small upstairs bathrooms, fan coil air handler and indirect dhw. 6 total zones. 

Originally quoted and approved viessmann vitrocrossal 300 cu3a-160 install. 

now installer put in the vitodens 100-w 150btu without my approval. 

They are telling me the 300 is over kill and I don’t have enough zones to justify that boiler. Is the 300 really unnecessary for my needs and will the 100 be as good? Would the 300 not be efficient with my setup? 

Jamie Hall

Haven't a clue. Has anyone done a heat loss analysis of your house? Without one, everyone is just guessing.

pecmsg

So the installing contractor is saying his 1st proposal was wrong?
This guy isn’t giving me a warm fuzzy feeling!

Hot_water_fan

That seems a bizarre situation to me! A Vitocrossal basically is a boiler + buffer tank, with the added bonus of no P/S piping. So they could install a buffer tank to make the options similar. However, Vitodens have a better turndown ratio so the buffer is less relevant. I suspect efficiency is a wash, but it's a bad look. What's their excuse for quoting one thing then changing their mind? By overkill, they mean the buffer isn't needed? They're essentially the same size output wise.

Mn1985

I called viessmann sales rep today and they agree the btu rating is good for the size of house and garage. Just can’t figure out why the 300 for installers mind is more commercial and overkill for my house. If both boilers have same btu rating why would 300 give me any trouble. 

And they didn’t tell me until I pointed out the boiler didn’t match the contract. 

Hot_water_fan

I called viessmann sales rep today and they agree the btu rating is good for the size of house and garage. Just can’t figure out why the 300 for installers mind is more commercial and overkill for my house. If both boilers have same btu rating why would 300 give me any trouble.

I don't think it's related to output - as you note it's the same. I think they didn't think you needed the buffer tank because you have several high mass zones (and a few low mass zones). They might be thinking that the buffer features aren't worth the money, hence the overkill.

GGross

Here is the input range for both boilers
100-w B1HE-150 15.5-150 (MBH)
vitocrossal 300 CU3A-160 43-160 (MBH)

The CU3A is a much more expensive boiler, it is quite impressive, but Viessmann really needs to update it for the US market. The firing range is not in line with what most are looking for these days, and while it does come with a wifi adapter it is a bit dated by homeowner standards. The boiler itself has many advantages for certain installations, it has a 0 GPM flow requirement and could technically be used in a gravity application, which not many condensing boilers can claim. They are high enough mass that they tend to limit short cycling that would occur due to the tighter turn down ratio.

The new 100 series (the one you have installed) is my favorite boiler right now. The control is intuitive without being overly complex like previous Viessmann models. It has the built in wifi everyone wants (even it's own wifi adapter so you can connect to it for commissioning without connecting to customers netowork) It has the wide turn down ratio that makes it a great fit for most sized homes, it has separate tappings to go to an indirect water heater which allows you to run a boiler mate, with in floor heat on the heating side without the need for a mixing valve. It looks nice, you can mount the control on the top so you aren't on your hands and knees to program it, and it is like half the cost of the CU3A


More than likely your installers wholesaler did not stock the CU3A, I can tell you not many do anymore. It seems to be left behind right now as Viessmann is focused on getting Europe off of dependence on russian fuel by pushing hard on their heat pump lines (Russia bombed one of Viessmann's facility so it is a personal thing for them rather than political) I know other wholesalers will sometimes contact me to purchase one-off CU3A boilers as they don't want to stock them.

Bottom line is, in my opinion you got a great boiler, now let's see some pics of the install and we can all critique that, as the install is far more important than the equipment

Mn1985

Ok I Will get pictures up later tonight. 

It good to get unbiased opinion on an odd situation that feels like a bait and switch to untrained homeowner 

Mad Dog_2

If its a big price difference then they need to refund $ or redraw contract.  Mad Dog 

Mad Dog_2

Uncle Richard..Mr Viessman Man...where are you?  Mad Dog  🐕 

Allislandradiant

I too would love to see the photos. The proof is in the pudding as they would say. The CU3A is a beautiful piece of equipment and we have installed a few. Yes, they are hard to come by and many wholesalers don’t keep too many around. They are priced more than the 100 and I would request to be refunded if he can’t explain why he made the change. The 100 is a good boiler, it’s a not a CU3A, but every boiler has a application for the emitters it’s providing for.

Mn1985

hot_rod

The piping look nice, plenty of valves. but the T&P valve on the tank may not be correct? The probe on it needs to be into the tank, and a discharge tube should be installed. Perhaps the job is not finished this pic?

Mn1985

They have some things to finish up. Don’t see expansion tank also 

Allislandradiant

Paul Pollets

The 100 is the "economy" entry level mod-con from Viessmann. It should also use a low loss header when flow rates exceed 7gpm. The CU3A doesn't require a LLH.

Mn1985

After doing some additional research i think the vitodens 200-w would be a best fit for the application. Since I have a fan coil and radiant floor I wont be able to have multiple heating curves for outdoor reset on the 100 and wont be able to use that feature. They plan on not even setting up the outdoor reset which I believe will just lose the whole purpose of putting in a high efficiency condensing boiler in.

GGross

Ideally you could use the viessmann mixing valves for the lower temperature zones, multiple ODR heating curves etc. The CU3A is also capable of that, however the 200-w (E series 200-W) also has the separate tappings for your indirect water heater, and the much nicer easier to deal with control. I agree the 200 is the better boiler, and a better fit for your application given the multiple temperatures.

You don't necessarily need the viessmann motorized valves, they can be costly to repair if they ever go bad but are nice for the complete package. I have found with the 200-w that using multiple heat demands each with their own heating curve, and a manual style mixing valve is adequate. The highest temp that is currently calling will be what the boiler targets, the manual mixing valve will then act as a limit for supply temp to your radiant zones, and when the radiant is all that is calling you will get the added benefit of lower temperature which = more condensing = better fuel savings

no matter what, make sure that they install the ODR. Even if that is all that they do, and they don't set it up correctly, you will be able to fine tune it later. But given that they quoted you a much more expensive boiler, I think a 200-w just might be the correct compromise

Mn1985

GGross said:

Ideally you could use the viessmann mixing valves for the lower temperature zones, multiple ODR heating curves etc. The CU3A is also capable of that, however the 200-w (E series 200-W) also has the separate tappings for your indirect water heater, and the much nicer easier to deal with control. I agree the 200 is the better boiler, and a better fit for your application given the multiple temperatures.

You don't necessarily need the viessmann motorized valves, they can be costly to repair if they ever go bad but are nice for the complete package. I have found with the 200-w that using multiple heat demands each with their own heating curve, and a manual style mixing valve is adequate. The highest temp that is currently calling will be what the boiler targets, the manual mixing valve will then act as a limit for supply temp to your radiant zones, and when the radiant is all that is calling you will get the added benefit of lower temperature which = more condensing = better fuel savings

So the 100 is unable to do multiple odr? just making sure. Thanks

GGross

100-w can accept a single call for space heating, with a single heating curve. it also has the separate call for DHW which makes a different temp (but this does not affect your setup as the DHW is a separate loop)

200-w can do multiple heat demands, each with their own heating curve, and it can do the DHW on the separate loop as well. So if you have 3 space heating temps, you would need 3 individual TT connections made to the boiler, in the setup you would assign each TT (the thermostat wire connection) its own heating curve based on the emitters chosen for that zone.



For your reference
you have
B1HE-150


You want
B2HE-150

The piping arrangement for both of these boilers is completely identical, the parts inside are identical, the control is different, and what they call the "Human Machine Interface" or HMI (thats the touch screen control lol) is different. You could pull a 100-w off the wall, and the same size 200-w (E series only) would fit exactly in the same spot with all piping etc lining up

Paul Pollets

You'll still need a Low Loss Header for hydraulic separation and higher flow rate. I've used as many as 3 mixing valves on their own curve and a DHW tank on the 200 and Cu3A models
. The curve on the 100 would need to be set to operate the air handler coil temps, which usually takes the boiler out of condensing mode.

Mn1985

Paul Pollets said:

You'll still need a Low Loss Header for hydraulic separation and higher flow rate. I've used as many as 3 mixing valves on their own curve and a DHW tank on the 200 and Cu3A models
. The curve on the 100 would need to be set to operate the air handler coil temps, which usually takes the boiler out of condensing mode.

They used closely spaced t but the contract stated low loss header. need to see the reason on that as well

Paul Pollets

Primary/secondary piping is not the best way to go but is sometimes used with the 100 to save money against the cost of the LLH. I get suspicious when the right method of piping or boiler isn't used. Viessmann is particular about how its systems are piped and why. There's an anacronym often used: RTFI
Read The F**&king Instructions

Mad Dog_2

No doubt you are getting a very nice job 👏. 
The installer should be amenable to making an adjustment.   Mad Dog

Mn1985

Finished product. Still need to discuss the lacking odr with the 100. I would agree install looks great just not convinced the 100 was the right fit For the fan coil and radiant. 

mattmia2

Can the 100 use a 0-10v input for setpoint? If so an external Tekmar control could accomplish the same multiple reset curve control.

mattmia2

Is this LP? If it is natural gas I'd double check the math on that gas line.

Mn1985

mattmia2 said:

Is this LP? If it is natural gas I'd double check the math on that gas line.

NATURAL GAS

mattmia2

it looks like it is 2psi gas to the house then a manifold and regulator on the other side of the room, but i'd check the tables to see if 1/2" csst can supply 150,000 btu/hr at that distance.

GGross

@mattmia2
my little gastite sliderule says at 0.5 PSI or less 1/2" WC drop we get only 131,000 at 5' of 1/2" gastite pipe.

mattmia2

It might be 3/4" but it looks like 1/2" to me.

Mad Dog_2

Richie Bruno, my BOCES teacher always said:  "Never supply any natural  gas appliance with less than 3/4 drop"!"   Its a safe rule of thumb.. Mad Dog

heathead

I don't see a shut off for the gas line near the boiler. Am I just not seeing something? Also a drip Leg.

Mn1985

Will verify size of pipe. Shut off is at regulator which is probably 6 feet from boiler. 

All good information and concerns. Without this resource I wouldn’t be able to understand what I now know about boilers. 

psb75

Compare: 1", 3/4", and 1/2" copper pipes under the boiler to the 1/2" black csst gas line. The 1/2" copper boiler-fill pipe is right next to the 1/2" black csst, right near the bottom right of the boiler case.

Mn1985

GGross said:

100-w can accept a single call for space heating, with a single heating curve. it also has the separate call for DHW which makes a different temp (but this does not affect your setup as the DHW is a separate loop) 200-w can do multiple heat demands, each with their own heating curve, and it can do the DHW on the separate loop as well. So if you have 3 space heating temps, you would need 3 individual TT connections made to the boiler, in the setup you would assign each TT (the thermostat wire connection) its own heating curve based on the emitters chosen for that zone. For your reference you have B1HE-150 You want B2HE-150 The piping arrangement for both of these boilers is completely identical, the parts inside are identical, the control is different, and what they call the "Human Machine Interface" or HMI (thats the touch screen control lol) is different. You could pull a 100-w off the wall, and the same size 200-w (E series only) would fit exactly in the same spot with all piping etc lining up

Can you help with how to wire the 4 radiant zones and one air handler. Looks like the 200 can do up to 4 zones and 3 heating circuits. 

Does that mean 3 separate heating supply or 4. Thanks 

Paul Pollets

When the 100 boiler uses multiple temps, the pumps are wired into a zone relay(shown in pic) with the associated thermostat and the relay will have an external demand terminal, which gets wired to the boiler. When the boiler receives the demand from the relay, it will fire. The ODR should be connected to the boiler and the control curve needs to be set for the air handler requirements. I don't see any thermometers downstream of the pumps?

Mn1985

Paul Pollets said:

When the 100 boiler uses multiple temps, the pumps are wired into a zone relay(shown in pic) with the associated thermostat and the relay will have an external demand terminal, which gets wired to the boiler. When the boiler receives the demand from the relay, it will fire. The ODR should be connected to the boiler and the control curve needs to be set for the air handler requirements. I don't see any thermometers downstream of the pumps?

The 100 is only able to supply one temp. Looking to use the 200 to get multiple temps to have multiple heating curves to get the most efficiency.  If I use odr on air handling curve it would over heat the radiant floor and burn unnecessary fuel  

Paul Pollets

Not if the mix temps are dialed in. Even with the 200, the air handler will dominate the temp requirements, but the but up to 3 mixed temps can be individually controlled with a separate curve + the indirect DHWT

mattmia2

Looking at the manual it could be controlled with a 0-10 v signal on what they call the "open therm" terminal from a building management system.

Mn1985

The house will be mainly heated by the floor. The air handler will be used when occupied. So I was thinking it would be most efficient if the boiler could run at lower temp for the majority of the time and ramp up when air handler calls for heat and not over heat the floor. 

House is a cabin that is usually used on weekends.