Buderus Logamatic 2107 with Hydro Air

AJinCT

I am here to try to help my parents set up their new Buderus Logamatic 2107 control on a G215/4 boiler with a matched Riello burner. The house is a 3800 sq.ft colonial, located near New Haven, CT, and was built in 2000. The house has 2.5 zone hydro air heating and cooling, running off of 2 Bryant air handlers, each with a fixed speed fan, and fixed speed compressor for A/C. The .5 zone is over the garage and uses dampers on the supply with a common return to run off of the upstairs air handler. They normally keep the downstairs at 59-62, the upstairs at 59, and the zone over the garage at 55, which won't come on unless they turn it to 61 to watch TV, because it gets enough heat from the other part of the zone due to the common returns. The actual temps are a degree or three higher, as their little round Honeywell thermostats aren't totally accurate.

A couple of weeks ago their Burnham V7 cracked, which they replaced with a G215/4 and a Logamatic 2107. They also have a Triangle Phase III indirect water heater, the square shaped one, I think it's either 40 or 50 gallons. There used to be 3 return circ pumps, one for each air handler, and one for the Phase III. The contractor that replaced the boiler initially set the system up on a rush job to get heat back on with a Honeywell 160/180 cold start controller, one Taco variable speed feed circ pump, and 3 zone valves, and the next week, when they installed the Logamatic, they put in a second, fixed speed Taco return circ pump for the Phase III, with the variable speed feed circ and 2 zone valves running the two air handlers, along with a bunch of other miscellaneous fixes to piping, purge valves, added glycol, etc.

The company that did the installation did a nice job with the boiler, piping, circulators, wiring, removal of old boiler and piping, etc, but they have very limited experience with any sort of electronic controls, like ODRs, the Logamatic, etc. As far as I gather, they pretty much put in boilers with 160/180 cold start controllers, and use mostly Weil Mclain, with some Buderus using the 160/180 cold start Honeywell controllers that come in the package with the burner and boiler from their supplier. The system works nicely, the hot water is more consistent than with the Burnham, the hydro air doesn't give nearly as much of a "blast wave" effect with the lower water temps as controlled by the Logamatic, and the Riello burner is significantly quieter than the old Becket.

However, I'm not sure that the Logamatic is programmed for optimum efficiency, as I believe they left all the settings at their defaults, or the defaults provided for American operation in the manual, other than turning the DHW to 120 or 125, as it is designed for cast iron panel radiators in Germany, which have entirely different operating characteristics than hydro air. On the flip side, with hydro air and fixed speed air handlers, they obviously aren't trying to get near-continuous circulation/operation at anything much above design since the savings in fuel oil from the ODR have to be balanced with additional run time on the air handler blowers. I have read through each of the three manuals and several threads on this web site and another heating forum, and I've figured some of it out, but I'm still working on a few concepts about how it works.

GW

Wow I sure hope you typed all that on an honest to Goodness key board. I'm gonna be less lengthy.

1, Europeans want it, we dont. Set it for 24 hr.

2, I read this a few times and I think you lost me. Dhw has nothing to do with odr. In general I think the 2107 isn't a great move for ahu.

3, ignore that. I guess it's if you forget to turn the heating on, the boiler will bring itself of and run the circ

4, differential size? Never heard of this.

5, I have a G125 at our office and we run radiant, very low temp. At 104 I made a mess all over the floor, it condensed like a sweaty pig. I cranked it up to 130 or so. But with your set up it should be fine. I still like to bump this up a bit, like 120. That's just me

6, put it wherever you want, lower the better as long as the heat works. Try 170. If that works, try 165. If that works....you get my point right?

7, same as point 6. Keep lowering until you're tired of hearing the ahu's run all day long.
With ahu buderus has recommended increasing day temp to 85 I recall (it's been years since I've seen a 2107 with ahu's). Then I think the offset gets Jacked to 9 I recall.

8, ahh it seems my memory still works. It's higher becasue when it's 50 degrees outside you don't want to be pumping 90 degree water to the ahu. That's the simple reason....you want hotter water

9, I'd leave it there, the ahu can make this setting pretty much useless

10, don't understand, dhw has nothing to do with space heating

11, now we're starting to split some hairs, I'd just leave it at 20. You could start playing with cfm on the ahu, which is fine if you have time to burn.

12, i wouldn't do a 2107 on an ahu these days. A 2107 by definition maintains heat yet ahu's don't run 24 hours like a radiant or radiator system.

I'm too tired to proof read, hope this helps.

GW

I've not heard the expression "compression' when talking about the 2107. In any case, you're worried about cycling when it's atime design temp? I would think the boiler would see some decent load and run some decent cycles.

that's a good sized boiler, pretty big home? It can't be too big if you're burning 1000.

I'd be surprised if you save 30%. It all depends on how clunky the old beast was.

BFU doesn't handle dhw. Dhw is set at the 2107.

Speaking of which, where is your BFU? I thought you had two ahu's? What's the BFU doing?

Gary

GW

Love the auto text on the droid, makes me seem like a poor typist

R Mannino

It's my understanding that the differential is fixed at 26 degrees on the the 2107. I will try to find the literature that I read it in.

GW

The pump logic number is the point where the pump will come on. It keeps the boiler from condensing. If your 2107 settings keeps the boiler in this low temp range, you're block will sweat and that's not good.

You have ahu, I'm sure you want hotter water than 104. Much hotter.

You need to crank your offset and day /night temps to get the boiler idling at 130 or so. I'd bump your pump logic up

2107 will lend itself towards longer run cycles than your previous boiler, that makes sense right? You should have your parents ditch the old school ahu's amd get modern with ecm stuff. Two speed or variable speed with 2 stage stats would be da jam.

Or you could go hog wild with Carrier Evolution stuff.

You're not going to get lots of lovin if you start a post with Buderus 2107 Compression Factors in your subject line, but you could always try.

G

GW

I'm unsure why you're hunkering on the max temp, you're talking the dial or the 2107, or both? If you're running lower temps you'll never see the boiker get that high, esp with a ref 148.

The pump logic, as long as you're not sweating you're good to go. But maybe I'm an old fuddy duddy, I like to raise that when there's a question of condensate. At my shop I raised it a lot

I see I confused my carrier lingo. I have done a couple Evolution Extreme ahu hp installs. Cool stuff. I'm mostly a Daver Lennox follower.

G

njtommy

A high efficiency heat pump like the Lennox, carrier, tranes are really nice. Trane Tam 7 is one of the nicest ahus I've ever seen. Solid as a rock and thick. Trane even offers a hydroair coil for the Ahu. Definitely cut down on all oil usage a lot.

Don't worry my Dad doesn't listen to me either. Lol

njtommy

I know the Trane will. Not sure on the Lennox, but I would imagine it does.
I think the Mitsubishi goes to like -10 now for the hyper heat or something crazy.
You could probably get hot water for almost free all summer with a tube bundle or other type of refrigerant to water heat exchanger. They pipe right into the discharge line. Then I would recommend an ICM fan speed control to keep you heat pressure high enough for the txv.

njtommy

It's desuperheating but it's also starting to condense your refrigerant. So it would be subcooling your refrigerant. Instead of the Hot gas coming out of your compressor and going straight into your air cooled condenser it would go through the heat exchanger first. Then back out to your condenser. so that way and refrigerant that was not converted to a liquid would have a chance to become a liquid.

njtommy

http://www.hotspotenergy.com/heat-recovery-technology/

njtommy

Depending on pricing it's kinda of silly not to use it.

GW

If you're fine with the boiler water temps in the mild weather days then you don't need to change the shift and the sun moon temps. The general idea is ahu needs a boost in water temp when it's not cold outside

SWEI

Less so for a variable speed ECM. Retrofits often make sense.

GW

Yes that's been rhe premise of the whole chat right? Finding the most appropriate temps is always the goal

We know those hogs are sucking several hundred watts of juice each. Ducts....are the poor, ok, good, or superb?

You may save energy by adding heat to the boiler and lowering the fan speeds

njtommy

Should of just installed Daikin Atherma system. One stop system does it all.

njtommy

I figured it would be up your alley. I briefly looked into it for my own house before deciding on natural gas.
My house is only 1800sq ft with a heat loss of 45K not including garage and 4 seasons room.

GW

What are they claiming for cop?

So many pros, so many cons

You're right, nat gas is cheap. I did the math on my bill at home recently and came up with $1.04 or so (it was one o something ) a therm. That is crazy cheqp. I did it twice, I couldn't believe my eyes.

Local oil co has a lit up board (like a gas station), oil is $1.66 gal.

njtommy

This was before I had gas ran to my house. I looked at geothermal too, but starting to look like way too much money to install for what I was after.

Yes Gas is pretty cheap. I'm $1.09ish last I looked. My buddy has oil he just paid $1.55 per gallon. I just installed a Crown 3 pass boiler for him in the fall. Was hoping to do a little testing this year for fuel savings, but is been so warm it's too hard to tell.

SWEI

From last month's NG bills here in NM:
$0.515 (residence, consumed 73 therms)
$0.406 (hotel, consumed 2108 therms)

Very tough selling efficiency to those customers right now...