Important question re: Adjusting Mod/Cons

Constantin

... but I need to find the time first to figure out just how I ought to shift and incline the curve. Below is a summary of the last 8 hours of zones calling. You can see the Tekmars doing their duty...

As Zone 3 is probably the one with the highest BTU/ft² heat loss, I imagine that I'll lower the curve until the Z3 pump is on almost all of the time. I have yet to mess with the Thermostats in that section (they're a newer model of Tekmar that I find quite unintuitive compared to the 062's they replace) to ensure that the temperatures reflect where I want them to be.

Mike T., Swampeast MO

Do you ordinariily give homeowners access to and instructions for adjusing the reset curve (slope & shift)?

Is such reasonably simple with most mod/cons? Does access to the reset curve also open a path to critical settings that might be inadvertently or improperly changed?

If you don't give access/instructions, why not?

Guy_6

Adjustments

I am coming at this from a different angle, having worked for a Mod/Con Manufacturer:
I would NOT allow homeowners the access to the curve because they would have too much opportunity to create headaches for both themselves AND YOU!
Two analogies:
1) "OK Mr Homeowner, how many times did you press the reset button (on oil fired equipt)?" The answer that you get is usually incorrect (translation-singed eyebrows). The same would run true with their explanation of how they set the curve. Their interpretation of the reset curve may not be realistic, and if it doesn't work out correctly,they have lousy heat,or a freeze up, and both the equipment and you look bad.

2) How many times have you had complaints that the t-stat was set at 68 and the heat ran to 69, or 66-whatever.
I can feel the phone calls-"By my calculations on an X degree day my boiler should be opeating at Y".

I think that Ron Popeil said it best-"Just set it and forget it." You know what will work in your area- the homeowner probably won't.

JMHO

Guy

Plumbob

I'm a homeowner. Before signing a contract for our Munchkin, I got a commitment that I would get ALL manuals and instructions. I'm paying for it, after all! If you told me not to worry my pretty little head with the reset curve, well, that would be the end of the discussion.

There is a good practical reason why the customer needs to adjust the reset curve. How can a contractor set it correctly? You have no idea what the right reset curve is for this house. It has to be adjusted based on regular observation, using a stat that displays heat call durations each day. Without this, you are setting a very "safe" curve that may prevent callbacks but is not much better than not having reset at all.

One of the things I learned was how primitive the Munchkin's linear "curve" was; you can never get it right for both warm weather and cold weather. You need a curve that is actually curved.

Brad White_9

Wow

That is one good response!

Well said, well stated.

Brad

Constantin

I insisted to learn more...

... and I was richly awarded for doing so. Taking the controls class at Viessmann was incredibly rewarding and illustrated to me how little my contractor had done to change the initial settings on the boiler. For example, Ms. Vitola was running on its initial 1.5 (?) curve... That is not to say that my contractor didn't have plans to adjust the boiler at some point, but the boiler had operated for months on the higher curve in the meantime.

The reset curve/offset controls on the Vitotronic 200, 300 are incredibly easy to adjust, so any reasonably competent home owner ought to be able to adjust the values with little difficulty. It's easy enough to walk them through the steps via the phone.

I made a point of creating a list of all parameters in a Word file that I have printed and left next to the boiler. Re-programming all values into the Vitotronic would take maybe 10 minutes once you have a list that shows all the values you're going to see in the order that they'll appear.

I also like how Viessmann gives you some good ranges to start with re: reset curves based on emitters and home construction types. These are safe values... IIRC, they recommended a 0.8 curve where a 0.5 seems to be sufficient.

Mike T., Swampeast MO

Thanks for Replies So Far

I've been asked by more than one person now to write instructions for adjusting the "base" curve of condensing/modulating boilers for utmost efficiency then fine-tuning for lifestyle.

Obviously I can't include specific instructions for each boiler/system.

So, if common contractor concensus is that "they shouldn't be messing with the curve" such is pretty much a waste of time as they won't even know how to access.

Looking forward to more comments!

John Ketterman

> That

> is not to say that my contractor didn't have

> plans to adjust the boiler at some point


Oh sure, he probably already had it on his calendar for 2029.

hr

It depends on the homeowner

not all are digital or computer savy It the homeowner has the ability, or willingness, I say go for it.

Actually some of the enginers and electronically bent homeowners I have worked for are better at understanding the concept and adjustments than I am

Lochinvar is supposed to have a homeowner program available for a laptop, to be used on the Knight. Doesn't allow them into all the windows, but enough to fine tune a bit.

hot rod

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Mike T., Swampeast MO

That's the kind of thing I'm looking for...

Does accessing the reset curve in the Knight (or other mod/cons) ordinarily open up the programming to everything? Or is the curve (or can it be) accessed by a "less deep" mode or password?

Heating curve in the Vitodens is intended to be adjusted by the homeowner--completely separate from "deep" programming by the contractor.

Guy_6

perhaps

Perhaps I was a little too forward in my response:
Yes, there are some homeowners that I would trust with setting the curve, but then again there are some that I wouldn't mind installing the boiler either.
Then there are THE OTHERS.
I am sorry if I offended anyone, but I have been around this block a few times. I think that going around so much has made me dizzy.....

Mike T., Swampeast MO

No offense to me Guy. That was part of the answer I expected.

BUT, do you believe that homeowner adjustment of the reset curve could in any way cause harm to the equipment?

I do understand where you're coming from when you say that "I know the settings that won't cause a callback", but such settings with a condensing/modulating boiler are likely quite high and the homeowner won't be able to get the maximum efficiency from their boiler and for their particular system.

Do you as a matter of course include some "adjustment" calls as part of the installation price of condensing/modulating boilers? Unless you've installed MANY such boilers and spend LOTS of time with the homeowner, I seriously doubt that you can instantly know the perfect curve for both the structure and the homeowner's lifestyle.

Mike T., Swampeast MO

And I DO understand there will be a few homeowners who have no business accessing ANYTHING in their heating system save the thermostat(s) or TRV(s).

There will also be some who aren't really concerned with maximizing efficiency as long as they get the comfort and response they expect.

But for the rest--and I bet it will be a majority--why not give them the ability to be in full control of their fuel consumption and comfort?

If the Eurocave taught me anything, it's that with a condensing/modulating boiler I'm in FULL command of my energy consumption! The more I want to save, the more I do save!

Mike T., Swampeast MO

0.5 ratio in your house?

Have you tried lower? That's the ratio I'm using with standing cast iron rads that seem to have been sized by the "Mills Rule"!

Considering your exceptional insulation and infiltration control (well beyond average for new construction let alone an old house), I'd try 0.2 and work my way up.

If you used those spreadsheets that you kindly purchased from me, adjust down until things just go infinite...

chuck shaw

When I was doing installs

on a regular basis, I would work with the homeowner, and ask them if they wanted to read the manuals. If they did, great, I would show them the initial set up that I was using. I would give them the information to make an informed change. I wrote down what I had done, and asked that if they made changes to do the same so that performance could be plotted. I was amazed at the number of calls I got from excited homeowners telling me "I dropped the water temp another 3 degrees, and the house is still comfortable". I would also figure in at least two return trips to try and tweak the system. I would try and do those trips, to the best of my ability, when it was very cold out, and another when it was more temperate. This was with either type of homeowner.

I also think, that one of the more important questions that I asked the homeowner, was "What are your expectations of the system" if they wanted to set the house to 78 and think they were at the beach, that is what I tried to design for. I also learned that I wanted to drop my design temperature a little below the "normal low".

I followed the design parameters in a computer program in a room in my parents house, when it is 5 outside (local design) the addition is fine, however, on occasion, we get down below zero, and I do get that gentle reminder that "The new room is a little cool".

Chuck Shaw

John Ketterman

I assume every manufacturer does things differently. The Munchkin doesn't have the best-designed boiler firmware in the world, but it does have what could be called a basic/homeowner menu and an expert/installer menu.

The selection of items that can be changed is quite strange. In the basic menu (not password-protected) you can change only the top of the curve, not the bottom, and you can only lower it, not raise it. (I have no clue why.) You can also change the 'aquastat' differential (why would the homeowner be specifically allowed to change that?) Everything else has to be changed via the 'advanced' menu, which is protected with the 925 password.

I should add that while buyers should get all documentation, nothing requires you to write up simplified instructions for them. If the homeowner can't figure out the manual (which is probably not written in English---the Munchkin's certainly isn't), then they should not change anything.

Brian_18

I have another HO Perspective

I'm one of those guys that demands to know how everything works that I own. This is why the very next purchase after buying a car, or power implement is the factory authorized Repair Manual.

My concern here is the people that DON'T have the aptitude for tweaking their reset curves.

If the HO doesn't do it, and the installer's attitude is "set it....and forget it", how does the HO reap the full benefit of optimizing the reset curve?

I would think the installer would need to do this, but DO YOU?

I know from my experience, I find the need to change my reset curve at various times during the heating season. Depending on the calendar (sun position), the heat gain in my house varies depending on the month. I therefore make changes to the reset curve.

It seems if NOBODY is doing this for the HO, they are being short changed for the exact item that most likely was used as a sales feature, BEFORE the sale.

How many follow-up visits do you guys (installers) make for these customers?

Mike T., Swampeast MO

Z3: Is it common space? Since Z3 is the GREAT perponderance of the calls, I [think] you'd want to adjust your curve such that it's running nearly constantly.

Z2: Why no "tops"? Is the circulator frequently running for extremely short periods?

Did you get acceptable response to your heat call on Z1?

Constantin

Good Points...

... like I said earlier, I have to download, print, and comprehend the Tekmar manuals for these new Tstats that control Z3. That zone used to be on one Tstat, we split it into two w/zone heads because the north side of the building was always 5-10°F colder than the south side when the sun was out.

The reason that Z3 stands out is that the room with the T-stat has 3 exposed walls, and a partially exposed ceiling + floor. Thus, it'll always have more heat loss than the rest of the house.

As for Z2, I have no idea why it runs the way it does. That zone also has a lot of solar gain. More later!

Mike T., Swampeast MO

Too bad that FHVs didn't pass the "aesthetic design department".