your thoughts part 2

Mitch_4

Was looking for that link

Mitch_4

reposting the result from the original thread for commentary

as my posting seems to have been in the middle.

Here is the result: we reached
no resolution despite "evidence". My aurguments winning more points, but he refuses to capitulate on all fronts. (;-o)

Thanks for all responders, and I look forward to the additional comments after you read this.

We both concur that the COMFORT level will be greater in a mod scenario, but comfort is not consumption. Nor was it the topic of debate..

My position was that the mod wins, and that is more evident in a multi zone scenario. Energy must be used to heat the exchanger before it transfers heat to the medium, it saves fuel to do this once in a modulating boiler, the bang bang must do it every time.This is wasted energy that does not heat the structure..

His position was that heat loss is all. Heating plant makes no difference. If you lose heat you must replace it.

If the structure loses 50,000 btu's / hour, then it takes 50,000 btu's to heat, whether bang on/off, or modulating down and running longer. He feels most high efficiency boilers, the energy required to heat the exchanger is practically negligible. He stands firm on this in anything 2 zones or less if approximately equal sized.

The "evidence" he cited is that NRCan (Natural resources Canada) has done this exact test (although with forced air) and they were the SAME!! In fact the fixed unit with a PSC used a tad LESS than the ECM (gas only, electrical was cheaper with the ECM) because the heat generated by the motor is significant enough to save gas. (How do you factor THAT into heat gain?!?)

The NRCan test esentially proved that heat loss is all, all other features improve comfort. I have no evidence to support me so he feels he wins even though he concedes some points on multizones (however he says a buffer tank will nullify the mod boilers advantage there too and is less techno!!)

My buddy will agree that in a multi zone system (3+)the mod boiler will save fuel as it can match the load, but remains steadfast that a single zone system, will be a wash between them, and properly done a buffer can still beat the mod in a multi zone without all the fancy technology.

I say mod in both, but I can see his point in a single zone systems ONLY. In fact...In a one zone system, the savings to me are slim enough to not really justify the additional expense of modulation technology, and I do a brisk business with fixed input & ODR for these systems, based on the payback on modulating will be way longer than I feel is justified.

the NR Can test seeems to bear true only for single zone as that is what most forced air is.

This similar to that old debate here of FA or HWH. if both were 90% efficient it should be the same costs.. where HWH saves is because of comfort. you can set the stat lower in HWH, decreasing the delta t inside to outside the structure. but if both systems were to maintain the same temp, theorhetically it should use the same fuel. (But you would be uncomfortable inthe HWH structure cuz it'd be too da*n hot..

again the Q was costs though, not comfort level.

Brad W and Mike T, I am particularly interested inyour thoughts as I truly respect your opinions and views as some of the most intelligent and well thought out here on "The Wall"

Any other supporting evidence that can be dredged up would be appreciated as well.

Now that you know our positions and the "evidence" what are your thoughts?

Mitch

jp_2

gross error

""""His position was that heat loss is all. Heating plant makes no difference. If you lose heat you must replace it.""""

this is a gross error, although the heat lost within the "living space" must be replaced, theres a great difference as to the efficiency from the gas pipe to the living space. how well does this transfer take place, or how much energy lost out the chimney, etc...

still did not answer the question, "what is the running system temp of the non modulation system?" this does matter.

this also, does not make good sense:
"""My buddy will agree that in a multi zone system (3+)the mod boiler will save fuel as it can match the load, but remains steadfast that a single zone system, will be a wash between them, and properly done a buffer can still beat the mod in a multi zone without all the fancy technology.""""

you are still neglecting the energy required to heat system to higher temps than needed in non modulating system, especially in shoulder season, spring/fall.

Mark Hunt_6

The catch here

is that your friend is assuming a constant btu requirement. On design day, one could argue that steady state efficiencies for both units would be close to equal.

All systems are designed around the worst case scenario, a scenario that rarely happens and when it does it does not last forever.

Couple that with "questionable" heat loss/gain calculations and the math gets even fuzzier.

On top of that, unless Canada has been practicing human cloning, no two households will ever be exactly alike. As soon as you add people to the equation, all bets are off. The 70+ year old couple like to keep the stat at a balmy 75 degrees while the D.I.N.K.S (Dual Income, No KidS) next door enjoy wearing sweaters and wool socks and leave the stat at 58 degrees. Same structures, different heat loss.

Ask your friend to explain how a boiler/furnace firing at 100k input will burn the same amount of fuel as a boiler/furnace firing at 30k input. Why bother making equipment with different output capacities if one size fits all? Why bother with heat loss calcs if a 1 million btu boiler/furnace will work as efficiently as any other in any home?

Mark H

Mitch_4

THAT is

what I said.

His rational is that say the boilers are sized for a design day requirement of 100,000.

in a shoulder season wher it is say only 50,000, the modulating system will ramp down and run for 1 hour.

The non mod high efficiency will run 30 minutes..only difference is temp swing will be negligible for the mod unit, greater for the non mod, meaning greater COMFORT ina mod unit, but that was not our debate

UniR_3

Mark... check this \"oot\"

The houses themselves are clones and occupied by sensors...

http://www.nrc-cnrc.gc.ca/multimedia/picture/engineering/nrc-irc_ccht_e.html

They are very much identical and the internal loads are kept the same. It's just too bad that they don't have rads and such.

Doug_7

Do not misinterpret the NRC study

Mitch - Your friend misunderstands the NRC study.

The test was on two identical houses each with identical forced air furnaces, except the one difference being that one furnace had a fan with a high efficiency ECM fan motor, while the other had a fan with conventional PSC fan motor. The test of the otherwise two identical houses was run over months with a wide range of seasonal conditions.

Not surpricingly, the ECM fan motor provided a large saving in electrical consumption. It saved so much electricity that the house with the ECM motor actually used a bit more natural gas to offset the fact that there was not so much electrical heat losses being generated by an inefficient furnace fan motor.

This NRC study shows that ECM fan motors are much better than PSC fan motors. This NRC study does not compare modulating boilers and ON-OFF boilers and does not prove that "heat losses are all".

The efficiency of the heating plant enters directly into the gas use equation. If the heating plant has a higher seasonal efficiency, then the gas use will be lower that the same house with a heating plant with a lower seasonal heating efficiency.

To propose that a modulating boiler has the same seasonal heaating efficiency as a ON-OFF boiler is nonesense. They may both have the same efficiency at 100% firing rate, but that is only one point on the efficiency curves. In the real world, a boiler seldom runs at this point.

As the seasonal heat load drops to say 50% of boiler capacity, the efficiency of the modulating boiler will increase and the efficiency of the ON-OFF boiler will decrease (see manufacturers literature). The ModCon will use a lot less gas than the ON-OFF boiler for the same heat output.

To make the arguement that the boiler efficiency of the two boilers will be the same under all seasonal conditions is to not understand the operating characteristics of these boilers, that make ModCons a great technology improvement and a great way to save gas compared to ON-OFF operation.

I am saving 30% on my gas use because I replaced my ON-OFF boiler with a ModCon.

Doug

Unknown

really?

so, what's the exhaust temp of the two systems?

That's energy too.

PJO_5

Here's something \"Real World\"...

I replaced an oversized non-condenser with two mod-cons...oil to gas and split the two apartments. The previous boiler had heated both apartments.

I did no increase in energy efficiency to the structure as far as insulation/etc. besides the heating plant replacements(s). I also ripped out the 50 gallon gas HWH and put in a 30 gallon TT Smart indirect for each apartment.

The usage of oil was between 1,000 and 1,200 gallons per year for both apartments. At today's prices that would have been about $3,500.00 or about $300.00 per month for heat and hot water for both apartments.

The one apartment is mostly unoccupied (we use it in the summer mostly), and the gas bill is $25-30 per month through the winter.

The other apartment has a small child and the parents work first/second shift so it is occupied nealry all the time. Their gas bill - both heat and hot water - is $90-120 per month through the winter.

Glad I did it last summer - would have paid dearly for heating oil this past season ;-)

hootananny

Doug

just a couple of qick questions, how long have you had the mod/con?
Have you had its annual service?
If so, how much more was the service cost then the old boler,
leading to, how muc did you save in money over the year?
the Hooter

Doug_7

Cost Savings

Cost saving is about $5,000 per year on natural gas alone. Saving another $500 on electricity because I don't have to run the old atmospheric boiler recirculation pump. This is a multi-family condo.

Annual service should be under $500. What do you think ??

Fuel is our largest cost by far. Fuel cost savings over 5 years exceeds the total installed cost of the ModCon boiler. Gas prices are up 40% over the last year and will continue to rise. Everytime gas prices go up we save more money.

Doug

Mark Hunt_6

Thanks for the link eh! (nm)

Mitch_4

You all preach to the choir here

I believe in Modulation99% (single zone baseboard under 60k, not so much unless I can repipe to a multi zone)(that is the 1%)

Larry (from OSHA)

more real world data

I've just been through my first season with a mod-con. The savings are better than 30% over a somewhat oversized cast iron boiler with ODR. The amount of time spent firing under 50% rate verses over 50% is in my opinion significant. 2073 hours under vs. 840 over. Sometime this summer I'll open it up and clean it out and I suspect that there won't be much to deal with. We'll see and I'll have pictures then. This system is 3 zones of fin baseboard that has provided 70 degree comfort with water temps well under 160. Design temp 180 at -22.

Larry

Doug_7

Good Data Larry

Good data Larry. Thanks for presenting it.

I learned a long time ago to "Respect the Facts as shown by the Data".

It is amazing how often people will agree when they use real data and how often they argue when using opinion.

I have a Design Temp of 140 at -22 with PEX in Gypcrete floor heating. Annual Heating Degree Days over 10,000. Had -38 degrees this winter and passed the test.

We agree on the magnitude of the cost savings with a ModCon conversion. A license to print money at today's high fuel costs.

Doug.