Installing old equipment...

Constantin

I have no idea what was specified nor what the owners actually said to their GC. But so far, I have a much easier time taking their word as the truth than the lone sample from the other side I got to experience thus far. Plus, I'm not sure that I want to get deeply involved either, other than providing a little technical support.

Your suggestion to look into the equipment prices charged is a good one, though not being in the trade, I'd have little to offer in terms of "right" or "wrong" equipment prices.

The question of defining "high-efficiency" is another good one. I'm sure that if any lawyers get involved, this will one of the bones they'll pick. I hope it never gets to that stage.

As for the question of having to ask for a Vitodens to receive one... I don't know if I completely agree, though I appreciate your point of view. Ultimately, homeowners who have a GC overseeing their home remodeling project put a lot of trust into the GC to do the right thing, particularly if they lack the knowledge on what to spec, and where.

In my mind, a good GC and his/her army of artisans, qualified subs, etc. will put together packages for the homeowners to consider and sign off on. Whether its bathrooms, kitchens, or even the shingles on the roof, it's not unusual to have a mini-conference about it first. As stated below, I have not seen any contracts, have no idea what was and what was not signed-off on.

But if we take a hypothetical case of a homeowner that expresses the desire for a very efficient heating system and sets no explicit limit on the cost then isn't it up to the GC to make it happen? Perhaps even without the need to mention a Vitodens by name ?

Constantin

... ever done it?

A friend is renovating house and allegedly got a "new" boiler installed. The unit in the basement is an Atola, which sounds like a predecessor to the Vitola, MY 2000, according to the nameplate.

Now, there is the possibility that the heating contractor reused the old boiler in the house, switched it to gas, and updated the near boiler piping (which is very nice) but my friend is convinced that they changed the boiler too. Given the lack of a burner port and external power burner, methinks that this is a gas-only appliance.

Were you to install a boiler that is a generation older than what is sold today, wouldn't you tell the customer?

PS: The Trimatik controller on it has the same look and feel as the current crop of Vitodens controllers.

[Deleted User]

One way to find out...

Contact the manufacturer with the serial number and they can tell you it's history, as far as they know it.

You could also be blunt and ask the contractor...explaining to his that you know the Ayatola is an older model.

ME

Constantin

Thanks for the tip...

I think I'll wait for that until my friend has had a meeting with the contractor. That should be interesting!

The Atola looks very different from the Vitola, I'll have to look into my TDMs to see how the HX is arranged in there. I also wonder how/if the contractor obtained a combustion analysis given that the unit has a draft hood at the back. I seem to recall Steve Ebels getting higher efficiency numbers than the 83% that the Atola is rated for. Presumably, this had to do with the return water temperatures?

My friend asked for a high efficiency boiler, so using a 6-year old Atola in a gas application seems like a step in a weird direction. Perhaps the hydro-air coils scared the contractor? However, they should have plenty of capacity at 140°F to heat the house...

.... we used the same insulation contractor, the houses are about the same size, and just two out of four coils in the basement would cover my design-day heat loss... so the system should be capable of running in condensing mode 100% of the time, AFAICT. But, I haven't run a heat loss and it'll be interesting to see if the contractor did.

joel_19

Atola

The Atola was not replaced by the Vitola. The AtolaRN was the predessor to the Vitogas 100 and is a fine boiler. New old stock boilers ,A/C units etc are everywhere in warehouses. I'd say it could be brand new but you guys should ask the contractor not us. WE sell older stuff all the time if that is the model he specked what's the problem??? We just sold an old 10 SEER H.P the customers happy to get it as they are retiring and didn't want to switch out the airhandler . 3 years old but brand new.

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Constantin

Ah...

Thanks fo the clarification. Wouldn't you agree though that using a 3-year old HP because it's a better fit for a house's duct system is a bit different though than installing a 6 year old boiler in a gut job? This place had NO infrastructure, they had a clean slate to start with. The gut job took place over the course of the year, so previous specifications are unlikely to play a role either.

The thing is, the pipe work quality is very nice, with some propress and some soldered joints. Equipment layout is logical, easy to follow, and plumb. The sheet metal work for the ducts isn't bad either. While the air handlers may be missing float switches to turn them off in case there is a clogged coil drain, they do feature neat work, high quality components like a Nortec humidifier, and even sealed joints.

The headscratcher though is that my friend asked for a high-efficiency appliance. Given the choice between a Vitogas predecessor and a Vitodens, I'm surprised that the contractor did not opt for the latter option given that the 140°F air handler coils should work well with a Vitodens.

Perry_2

Sometimes..

old stock can be a very very good buy...

Hmmm... if the owner was already in - or approaching sticker shock - and a potentially large discount was available on the "new" older model boiler compared to say, a Vitodens...

I wonder if the contractor might not have asked the homeowner if they would settle for a lessor efficient great boiler if they could save $$$$ on the installation. Perhaps the homeowner indicated yes.

All speculation, but everytime I have been offered "old" stock on equipment from supply houses it was at a good deal. While that was not heating equipment - I think the concept is the same.

Perry

Constantin

Thanks Perry

I appreciate your thoughtful points. The thing is, my friend has no recollection of a "special deal" being offered. Allegedly, the two of them asked for a high-efficiency boiler and the Atola in the basement is what they ended up with.

Indeed, older equipment can be perfectly good for a given application but the buyer should be made aware of it, no? The meeting today ought to be interesting.

Constantin

Wow...

I just had a rather interesting conversation with the local supply house / rep. My impression is that the battle wagons are being circled and this isn't what I was hoping for.

So, allegedly this Atola is a better match for the home because the coils need to be run at a higher temperature than their nameplate/rating temp in order to keep the occupants happy. But if a hydro-air coil is rated at 140*F and the combined capacity of said coils at that temperature can satisfy the heat loss, why would the occupants ever feel cold? I mean, wouldn't any air flow warmer than ambient or body temp feel warm?

A further justification for the AtolaRN is the two-stage operation, which is no longer available in that size range for a Vitogas. True enough, but if the client asks for the high-efficiency equipment, would you sell them the lowest-efficiency boiler available from Viessmann?

When confronted on that point, I was told that as of late last year, Vitodens' had not yet been introduced into the US yet and thus a Vitodens was not an option. I guess I must have been hallucinating at ISH, in Warwick, and while oogling all the beautiful Vitodens installs on the Wall for the last three years.

What a disappointing call.

ALH_4

Atola RN

As far as cast iron boilers go there is certainly nothing wrong with an Atola RN. This boiler is high efficiency for a cast iron gas-fired non-condensing boiler. Was this boiler used or sitting on the shelf for 10 years? If they were charged new Vitogas 100 prices, that seems like someone pulling a fast one. This sounds like a nice system, if it is what they wanted at the time. Did they know what they wanted? I dont think they can hold the contractor liable for not installing a "high efficiency" boiler unless the word "condensing" was used because this is a high efficiency non-condensing boiler. Selling someone a boiler that old without informing them of that fact may be another story, particularly if it was used.

A lot of people looking for a high efficiency heating system get something much worse than this. If the owners wanted a Vitodens they needed to do their homework and ask for one.

-Andrew

Uni R_2

To be fair...

The supplier only deals with the contractor. Who knows what the contractor said to the supplier? Who can blame the supplier for moving old stock? They get paid to do that.

What I find curious is why wasn't the boiler model part of the contract?


On the other hand...
How would a Vitodens 6-24 look next to it as the lead boiler in a multi-boiler system?

Constantin

You've hit it on the head

I'm not privy to all sides of the conversation, particularly the contracts. More may emerge with time.

Design and equipment decisions are tradeoffs by their very nature. All I wanted was a frank discussion of why this system was chosen. Besides the evasive manouvering, what bugged me particularly was the claim that as of last winter, the Vitodens had not yet been introduced into the US market?

It subsequently reduces my confidence in all the other statements made by the rep over the course of our call that I cannot verify as true or false.

I presume that a non-confrontational discussion with the actual contractor will be the best next course of action. They are the ones who ultimately specified/installed the system and the heat loss calculation is the next item on my "wanted" list.

Steve_35

The answer is no.

You said, "I mean, wouldn't any air flow warmer than ambient or body temp feel warm?"

The answer is no. I'm willing to bet you've heard about complaints from folks who've switched to heat pumps from oil or gas heat that the air is cold.

I almost always point out to a potential client the air from the new gas furnace will be colder than the air from the old furnace. I do that after having received complaints after the new furnace is installed.

Perry_2

The local contractors I dealt with all

felt that "high efficiency" means one of the more efficient cast iron boilers (85 - 87% efficient).

Condensing boilers are not much in their lingo... and they will tell you that the early ones failed (which is true) and they had to replace them; and that they are still experimental and not proven (if you press them).

Thus, they justify why they don't know about them - and don't want to know about them either.

Here comes your "high efficiency" cast iron boiler... (unless you have the guts and the money to stand up to them and really request a specific brand and type).

If you talk to the General Contractor you will probably here something like that. I'll bet on it. They probably feel that they delivered a proven reliable high efficiency boiler. Can you prove them wrong? Afterall - the Vitodens has not shown itself to last 25+ years yet (much less 50).


Perry

rucomfy

Generally....

these so-called "blowing-cold" air complaints can be traced to poor duct design. The dirty little secret of the HVAC profession. Many duct designs are an absolute disgrace. Why? because we forget the basics or choose not to do the Manual J Manual D Manual T. The air feels cool because of VELOCITY excessive velocity.

The same reason why clients say their home is always dusty with forced air. The rated velocity of filters are 400 feet per minute.... not 1000 fpm like many duct systems.
The air filter will never work and the next "filter" is the blower and the evaporator coil.

Heat Pump design is based upon the volume of air the greater the velocity the more prone to feeling cold. Since day one it has been recommended to upsize the register to slow down the air, yet most systems still use the same 4x10 register. If fact "heat pump design parameters are useful in heat or cool systems.

What temperature air do you need to heat a room to 72 degrees??? The answer: 72 degrees just lots of it.

If you are going to design forced air systems PROPERLY
you need to take the ACCA Courses for Manual J D T.

BTW that Duct-u-Lator in your truck.. when you design at 0.1 static what does that mean?????? or what does that little "e.q." mean??? (equivalent feet) that is 100 linear feet of duct no boots, no takeoffs no elbows no plenum T-tops.. all of which have resistance and equivalent linear feet allowances !!!

Learn the proper engineering. Take the ACCA Course. You have to own the knowledge. The right way is the only way.

rucomfy

Generally....

these so-called "blowing-cold" air complaints can be traced to poor duct design. The dirty little secret of the HVAC profession. Many duct designs are an absolute disgrace. Why? because we forget the basics or choose not to do the Manual J Manual D Manual T. The air feels cool because of VELOCITY excessive velocity.

The same reason why some clients say their home is always dusty with forced air. The rated velocity of filters are 400 feet per minute.... max Not 1000 fpm like many duct systems. Look that up on your duct calculator..
The air filter will never work and the next "filter" is the blower and the evaporator coil.

Heat Pump design is based upon the volume of air the greater the velocity the more prone to feeling cold. Since day one it has been recommended to upsize the register to slow down the air, yet most systems still use the same 4x10 register. If fact "heat pump design parameters are useful in heat or cool systems.

What temperature air do you need to heat a room to 72 degrees??? The answer: 72 degrees just lots of it.

If you are going to design forced air systems PROPERLY
you need to take the ACCA Courses for Manual J D T.

BTW that Duct-u-Lator in your truck.. when you design at 0.1" static what does that mean?????? or what does that little "e.q." mean??? (equivalent feet) that is 100 linear feet of duct no boots, no takeoffs no elbows no plenum T-tops.. all of which have resistance and equivalent linear feet allowances !!! Where do you see flex duct or interior chase bays for returns? (unless you have the ACCA Duct Calculator you will not find it)

Learn the proper engineering. Take the ACCA Course. You have to own the knowledge. The right way is the only way.

rucomfy

Generally....

these so-called "blowing-cold" air complaints can be traced to poor duct design. The dirty little secret of the HVAC profession. Many duct designs are an absolute disgrace. Why? because we forget the basics or choose not to do the Manual J Manual D Manual T. The air feels cool because of VELOCITY excessive velocity.

The same reason why some clients say their home is always dusty with forced air. The rated velocity of filters are 400 feet per minute.... max Not 1000 fpm like many duct systems. Look that up on your duct calculator..
The air filter will never work and the next "filter" is the blower and the evaporator coil.

Heat Pump design is based upon the volume of air the greater the velocity the more prone to feeling cold. Since day one it has been recommended to upsize the register to slow down the air, yet most systems still use the same 4x10 register. If fact "heat pump design parameters are useful in heat or cool systems.

What temperature air do you need to heat a room to 72 degrees???
The answer: 72 degrees, just lots of it.

If you are going to design forced air systems PROPERLY
you need to take the ACCA Courses for Manual J D T.

BTW that Duct-u-Lator in your truck.. when you design at 0.1" static what does that mean?????? or what does that little "e.q." mean??? (equivalent feet) that is 100 linear feet of duct no boots, no takeoffs no elbows no plenum T-tops.. all of which have resistance and equivalent linear feet allowances !!! Where do you see flex duct or interior chase bays for returns? (unless you have the ACCA Duct Calculator you will not find it)

Learn the proper engineering. Take the ACCA Course. You have to own the knowledge. The right way is the only way.

rucomfy

Generally.... that is a lame excuse..

These so-called "blowing-cold" air complaints can be traced to poor duct design. The dirty little secret of the HVAC profession. Many duct designs are an absolute disgrace. Why? because we forget the basics or choose not to do the Manual J Manual D Manual T. The air feels cool because of VELOCITY excessive velocity.

The same reason why some clients say their home is always dusty with forced air. The rated velocity of filters are 400 feet per minute.... max Not 1000 fpm like many duct systems. Look that up on your duct calculator..
The air filter will never work and the next "filter" is the blower and the evaporator coil.

Heat Pump design is based upon the volume of air the greater the velocity the more prone to feeling cold. Since day one it has been recommended to upsize the register to slow down the air, yet most systems still use the same 4x10 register. If fact "heat pump design parameters are useful in heat or cool systems.

What temperature air do you need to heat a room to 72 degrees???
The answer: 72 degrees, just lots of it.

If you are going to design forced air systems PROPERLY
you need to take the ACCA Courses for Manual J D T.

BTW that Duct-u-Lator in your truck.. when you design at 0.1" static what does that mean?????? or what does that little "e.q." mean??? (equivalent feet) that is 100 linear feet of duct no boots, no takeoffs no elbows no plenum T-tops.. all of which have resistance and equivalent linear feet allowances !!! Where do you see flex duct or interior chase bays for returns? (unless you have the ACCA Duct Calculator you will not find it)

Learn the proper engineering. Take the ACCA Course. You have to own the knowledge.

The right way is the only way.

Paul Pollets

AR platform

If the boiler is indeed an Atola RN, it should come with the Comfortrol RN control. That platform has been replaced with the Vitotronic controls. I've installed many of these boilers and have recently started to replace the older "Comfortrol" controls with the Vitotronic models. The local wholesaler offered deals on the RN when the Vito line was introduced 4 years ago. The RN is a very fine atmospheric cast iron boiler. I used the 2 stage RN in certain applications, and miss the ability to stage smaller models. Hence the Vitodens.

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Steve_35

All inn all, you're correct, but

there are many factors to consider. How much is the additional cost to install 3 times the ductwork? Is there space to install the additional ductwork?

Bottom line, can the occupants be made comfortable with low temperature air? Absolutely as long as the air flow is low enough.

However, The Wall has some problems making it clear to which post or which part of a post one might be responding to. That's why I specifically included what I was responding to, which was "I mean, wouldn't any air flow warmer than ambient or body temp feel warm?"

My take is, no, any air flow warmer than ambient or body temp won't necessarily feel warm.

So my question to you is, can you make an air flow of 72 degrees feel warm? Mind that's different than asking can you be warm in a room that's heated to 72 using a heat pump.

rucomfy

Sure can..

demonstate for yourself. Using your own breath. Blow into your open palms feels "cool" what temperature is it?
98.6 degrees F Now open your mouth and just sign unto your palms... now what temperature is it????

I think Dan once upon a time wrote an article about "the ice rink effect" which is similiar in theory, I think.

Any way heat pumps will always benefit from lower velocity systems as will just about any mechanical heating system.

Yes it may be true that newer gas furnaces tend to operate
at the lower end of the rated delta T for efficiency. But lowering the velocity or shortening the fan off timing may help.

Sorry, do not agree with your claim of 3 times something or other, cost I quess. A job properly done is just that, properly done.

BTW ever taken the ACCA course(s) or or you just quessing at air duct design?

I thought so......... Gotta go. later.

Steve_35

You said 72 not body temp.

My question was 72, not body temp. And of course slow enough breath on one's had would feel warm. Interior body is around 99 while the hands are around 85. No magic there.

We can argue design all day if you care. Yes, I've taken system design courses. Done Manual D manually. What a PITA. I much prefer using Right-Suite now.

Yes, you can slow down the register velocity to where you'll have barely perceptible air flow and it will feel more comfortable when you're heating. What do you do when you're cooling? If you have floor registers you better have enough velocity at the register to throw the air or you have pooling. Unless you have ceiling registers then you better have enough velocity when heating or the warm air lays on the ceiling.

The best of both worlds would be a separate system for heating and cooling where the needs for both can be met.

I noticed you've been dodging all around the question I responded to. Namely "wouldn't any air flow warmer than ambient or body temp feel warm?" Can you make air flow at 72 feel warm? Simple question.

Constantin

Thanks guys

I think the answers to your questions may actually become available tomorrow. Allegedly, we will get the heat loss calculation, which should put the whole system in perspective.

If, as I suspect, the house's heat loss is not that different from ours (since it's the same neighborhood, construction style, similar foam insulation and square footage) then the coils in that house will be oversized at least 30%, if not more.

Thus, they might be able to maintain a comfortable temperature inside the house with a supply temperature of less than the 140°F that the coils are rated at. Which, in turn, would enable the use of a condensing boiler.

Whether to bother with the installation/ retrofit of a condensing boiler at this juncture is a good question. For one, there is the expense of doing a boiler swap. Then there is the question of how to vent the thing. Thirdly, the rest of the system also needs to be taken into consideration, i.e. the IDWH, the pumps, and all the other emitters.

It's my colleagues call to decide what to do. All I can do is to try and have a constructive conversation with the folk who did the install. Hopefully, they will not be as evasive nor play as fast and loose with the truth as the supplier I spoke to on Friday.

Constantin

I'll have to take some pics...

... brain is leaky again. I'll get the specs to you. I think the 2-stage operation is neat also... but I distinctly remember reading "Trimatik" on the controller. It looked very similar to the 4-button Vitodens control pad that is currently in use - LCD and all.

I've only heard one side of the story so far, and that side allegedly asked for a high-efficiency system. While the Atola is not a bad boiler (far from it!), the question in the back of my mind is: if a client expresses a desire for high-efficiency equipment, then how do I make it happen?

If natural gas is my fuel of choice, a Mod-Con boiler is pretty much the only answer that makes sense as long as I can keep the return water temperatures below 120°F, right? Plus, the condensing boiler does not have to be Viessmann... plenty of people are happy with the other products that are out there so you could hit several price points offering good, better, best and allow the client to make an informed decision.

Paul Pollets

Efficiency vs mod/con

The RN boiler will require 4 way mixing valves for low temp applications or radiators, and possibly a boiler bypass, if water content of the system exceeds 3x the boiler water content. Gas supply should be a min. of 3/4" to achieve proper flow rate to gas valve. The boiler vent should be "B-Vent" to the chimney breach, with an insulated chimney liner, for best efficiency.

The "Trimatik Comfortrol RN" is the older model that came with this series. The newer computer is the Vitotronic 200 or 300. The Vitotronic can be adapted to the RN boiler with a special housing, supplied by Viessmann.

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Constantin

Thanks Paul!

Is there a significant difference in the Trimatic vs. the Vitotronic in terms of its capabilities? I have the vitotronic 200 in the basement and know it well, but know little about the trimatic...

The radiant zones are tiny... 3 bathrooms and the smallest 4-way I've ever seen runs them. Thus, the boiler should be fine/protected as far as the radiant is concerned. How low can the return temps go on an Atola before one has to start worrying about flue gas condensation?

Paul Pollets

AR water temps

like any cast iron boiler, the boiler should run to 140 within 5 minutes of startup. If not, a bypass is required, regardless of the 4 way. Often a system bypass is used across the 4 way return. Viessmann has a sketch available.

The RN control is a generation behind the Vitotronic. Just like any computer upgrade, the Vitotronic is easier to use and troubleshoot. The RN had it's early problems, particularly with the motherboard glitching. All motherboards were subject to recall and replacement. Make sure it's done.

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Constantin

The saga continues...

... I won't name any names... but there were a number of headscratchers to enjoy today.

The supply house did the heat loss calculation using a "slide rule approach". Thanks to many years of experience and countless hours in front of a computer, the supply house representative has come to the conclusion that the following approach works great in sizing heating systems:

• 20 BTU/hr/ft² for radiant floor heating systems
  
• 40BTU/hr/ft² for hydro-air
  
• and something else for baseboard.

So, if a house has 4,000 sq. ft of living space and hydro-air, then a 179kBTU/hr DOE output boiler looks just like the right ticket. Particularly if the heating contractor routinely adds on another 25% of capacity "just in case they want to build an addition later on".

BTW, the boiler was an extra-special sale to the contractor, as this supply house hoards them (allegedly cleaned out Viessmann when they discontinued the AtolaRN), "they do not show up in inventory", and are only sold to select contractors within the good graces of the supply house. Delivered with a straight face, no less.

According to the rep, even the use of Icynene only goes so far to ameliorate infiltration and those old windows also seep like crazy (even if they have a modern storm). Well, I guess I must have been hallucinating when I got a 0.20 ACH result with the blower door test in my own home despite old windows in 1/2 the house. And that's before I've even addressed the sealing issues remaining with a couple of storms and the mail slot too.

Overall, the heating contractor was pretty angry. He wanted to know "why the engineer was being brought in at the end of the project, not the beginning", which is a fair point. He eventually got so agitated that he stomped off without a further word.

The issue of cold air blowing, etc. also came up, just as some of you have mentioned also.

The Aluminum chimney flue they used is not compatible with a Vitodens, so that would probably require the use of a side-wall DV terminal since the flue is crooked and retrofitting a smooth-wall liner under those circumstances is more than a bit tricky.

I'm wondering if we can do some empirical testing over the next couple of months to see just where the occupants would feel comfortable. The supplier invited me to explain to the HOs how to use the reset controller on the Trimatic, which is also very gracious of him.

Yet I feel that this may be wrong time of year to be doing a unscheduled boiler swap, particularly if the HOs are trying to move in. If they keep the boiler for now, the testing may show just how often that second stage fires and whether the Vitodens is even an option.

This may be the best approach to handling any kind of follow-on drama in the first place, i.e. knowing what the heat loss really is, knowing what supply temps work, and knowing whether the folk on the other side of the story are full of it or whether they know what they're doing.

Much of what has been said runs counter to what I have learned here and off the wall, but I am willing to reserve judgement until I have all the facts.

Constantin

Thanks Paul!

That's a good thing to know. Perhaps Trimatics are just as valuable as Atolas, so the supply house should be happy to send us the "downgrade". :-P

Dave_4

Ask what it would take?

Constantin, why not just ask the contractor what it would take to get a Vito in there? That seems to be the required end state and the venting should work - right? The contractor could have gone down that road from the onset rather than appearing to have pulled a fast one, but you need to deal with the issues now. This venting could be a big headache. Maybe there's a simple mutually beneficial solution without everyone starting from opposing positions?

Not to mention it needs to be properly sized. Doesn't Mass. require that?

Brad White_148

Mass. Code

Spot-On, Uni. Some more digging to do.

It should be noted that 780 CMR Chapter 13 applies to buildings other than low rise residential construction but that R-1 buildings (hotels, motels) are considered commercial buildings insofar as the energy code is concerned.

Appendix J applies to detatched homes which fall under Use Group R-3 or R-4. Probably R-4 in this case, I gather, if it is single family and not over 3 stories in height.

Excerpts from the commercial code at least:

780 CMR 1305.2.2 Calculation of Heating and Cooling Loads:

"Design loads shall be determined in accordance with the procedures described in Chapters 25 and 26 of the ASHRAE 1997 Handbook of Fundamentals or an aproved equivalent computation procedure."

The term "approved equivalent" is to allow any software program so long as they are founded using the ASHRAE algorithms. Slide Rules are conspicuously not mentioned, but I imagine there may be one out there somewhere.

During orientation for the new code, they specifically told us the idea was to eliminate "back of a napkin" calculations. Let's see how this this applies to R-4 use group.

780 CMR 1305.2.2.1 Equipment and System Sizing:

"Heating and cooling equipment and systems capacity shall not exceed the loads calculated in accordance with 780 CMR 1305.2.2. A single piece of equipment providing both heating and cooling shall satisfy this provision for one function with the capacity for the other function as small as possible within available equipment options".

The last portion is obviously for packaged equipment, heat pumps and the like; not applicable to the boiler issue here.

I will do a little digging later under Appendix J to see what applies to this case, including common principles.

Hope this helps, Constantin.

Brad


EDIT: ASHRAE Fundamentals or Manual J and not over 125% of calculated load is what is allowed, not including standby capacity. See attached, J2 has this spelled out.

Paul Pollets

Hi/Lo staging

One thing to make sure of is that the boiler doesn't sit at low fire all the time. I promise you'll damage the boiler if only 3 of the 7 burners becomes the predominant load. The boiler will also tend to condense if the high fire doesn't come on often.

What a way to sell Viessmann boilers. That the heating contractor doesn't take full responsibility for design, sizing and specs is not a good thing.

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Constantin

Thanks guys...

... particularly Brad for uncovering the relevant CMR sections. I will pass them on.

Well, considering how special the RN is to the supplier, perhaps he'll happily take it back for an exchange with a right-sized Vitodens 8-32? Well, I can dream, right?

After a heat loss calc of my own combined with a bit of curve-tweaking, we should have a better idea of just how much this system is oversized. The curve will ultimately tell the story. At that point it is up to my friends to decide whether they want to deal with the fight or live with the Atola.

Constantin

Oh dear...

I hadn't considered that kind of a problem. I'll read through the Atola manuals I have from my Viessmann training to better understand the boiler. If can I use my home as a proxy for heat loss, then I *know* that the second stage will never come on (they would have a load in the sub-50's).

Even at 20BTU/h/ft² for a 0°F day, their heat loss would be in the sub-80's. Stage 1 is 79kBTU net, so the only possibility of that second stage coming on is someone using a heck of a lot of hot domestic water. Indeed, the Vitodens that Andrew recommended as a first stage may in fact be all that's needed to keep the house warm.

As for the contractor, he was also adamant that radiant floor heat doesn't and couldn't work in older homes under wood. Thus, only the bathrooms are served by radiant. I felt like bringing him over and proving him wrong, but he was so defensive to start with, I doubt it would have done a whole lot of good.

I wholeheartedly agree with you that this caricature of a supply-house-contractor relationship should not exist, but as long as contractors don't care, they put themselves at the mercy of someone that may or may not have their best interests at heart. Never mind the homeowner, who is even further down the food chain as far as the supply house is concerned.

Revealingly, both contractor and supply house rep listed "no call backs" as their number one priority. No wonder that they install oversized equipment as a rule, as efficiency is of no concern to either. From my perspective thus far, the rep is a loose cannon. The contractor could probably benefit a lot from a couple of seminars, books, and other forms of information.

Paul Pollets

training vs sales

a little off topic, but many contractors don't make the time to learn how to calculate the loads for system design. Deferring to the wholesaler has limitations, paticularly the experience of the heating sales guy. Many wholesalers have sent their inside sales guy to the basic design courses, who then seem to practice "rules of thumb". Experience is hard to find. My father's company used to employ mechanical engineers to specify and design heating systems. They had vast experience in the world of hydronics and steam. Ask Dan H. It's not done that way anymore. No wholesaler wants to pay for ME's fees. Too much "overhead". Train the counterman and away we go....

How come in Boston you're not dealing with RST Reps?

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Steve_35

Ain't it the truth, Paul.

I looked at a job a couple of weeks ago installed by a plumber with directions from the local supply house. 1000' of 1/2" PEX on a single loop spaced 16" OC in upstate NY.

The same supply house told him, the plumber, a gallon an hour oil boiler would be just fine for a new 2400sf house.

Constantin

Hi Paul!

I agree that companies have been cutting "overhead" as much as they can... and that is true for many industries. One of my former clients were calling the graduates of 2-year drafting schools "engineers"... while experienced engineers were let go... with obvious results when it came to designing new product... no one had a clue.

Meanwhile, they were wondering how come they had not released a new product in 15 years and why the margins were so bad. A textbook case of running a business into the ground by allowing the shortsighted beancounters to run it.

Anyway, I had no say in any of the decisions on this project but if I see the GC, I'll make a point of asking him about the supply houses he choses and why. I'm not going to name any names because the point of this thread is not to embarass folk out there. What I really want is my friends to be happy in their home.