Fine tuning new ES2 Boiler

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Old 01-04-14, 12:04 PM
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Question Fine tuning new ES2 Boiler

Hi,
I have found lots of useful information here about installing, running, and troubleshooting boiler installations so I would like your opinions and advice about my situation. I purchased an ES2-5 boiler just a few days before the end of the gas company rebate program in May 2013 and unfortunately did not find this forum until after it was installed.

I converted from oil to gas in June 2013. No changes were made to the heating system other than substituting the new boiler for an oil-fired Burnham that was installed in 2000. I think that one was rated 160,000 BTUH. My previous system used an average of 800 gallons of oil per year in the last five years. I estimate that is a rate of about 39,000 BTUH using a 4-month heating season. The new gas ES2-5 is rated 140,000 BTUH input, 119,000 output. Three contractors independently selected that boiler size after visiting the site. No heat loss calculations were done.

My house is a wood frame, 2-story shingle style house built in 1912. It is 2230 square feet and 19,294 cubic feet. The exterior walls were insulated with blown-in fiberglass in 1973. The original double-hung windows were replaced with energy efficient windows in 2013. All other windows, sliding doors, etc. are double pane thermal but 25+ years old. The attic was expanded and converted to a master suite in 1986 and the walls were insulated with R-11 fiberglass AND foil-faced rigid foam R-6.5 (for a total insulation R-value of 17.5). The ceiling (roof) was insulated with fiberglass R-13.

The original heating system was gravity hot water with cast iron radiators converted to forced hot water in 1973. Domestic hot water is from a separate gas-fired hot water heater. I also run the range, fireplace insert, and clothes dryer on gas. I am considering a generator in the future. The gas company installed a new gas main and replaced the service line into the house last April.

There are three heating zones each with separate Honeywell electronic programmable thermostats and Taco 007 circulating pumps:
(1) The first and second floors with mostly cast iron radiators except the kitchen/dining area which is a mix of cast iron, fin tube recessed into wall niches acting as convectors, and some under floor radiant PEX tubing.
(2) A 130 s.f. greenhouse with 90 feet of fin tube around the perimeter and in the joist spaces under the floor.
(3) The third floor master suite with 68 feet of fin tube baseboard and radiant PEX tubing in the bathroom tile floor. Due to the piping configuration from the boiler and the later addition of the under floor radiant, this zone has two thermostats and a three-way valve to isolate the under floor heat. One thermostat controls flow to the bathroom only (PEX under backer board and tile on insulated wood subfloor, and 3 feet of baseboard, in parallel), and the other sends flow when needed through the remainder of the suite and then through the bathroom to return to the boiler.

After the boiler was installed (and after reading many posts here) I calculated the heat loss as 1038.718 BTUH using on-line resources. Using a design temperature of 0 degrees (I am in the Boston area but added a safety factor) this translates to a 72,710 BTUH need. (At the 10-degree design temp for Boston it would be 62,323 BTUH.)

It looks like I fell into the oversizing trap that is well documented in this forum. I dont really have buyers remorse given that I expect to save 40+% in heating cost due to the lower price of gas but I would like to run the system as efficiently as possible and avoid maintenance problems. I opted not to install indirect DHW from the boiler at this time due to the excellent condition of the existing HW heater (I replace the anodes regularly) and the added installation cost, but will consider it when the HW heater needs to be replaced (or as a possible load addition to the boiler sooner if the information here indicates I may expect major boiler problems in the near future.)

The new boiler did not come with an ODR so I kept the one I already had, however the water temperature sensor is not installed in the boiler but in the supply manifold. This causes a slight delay in ODR control because the bypass reduces the temperature of the boiler water going into the supply manifold and the boiler runs up to its high limit before the ODR can shut it off. I am still adjusting the ODR ratio to overcome this.

Also at the end of October when the need for heat became consistent there was a problem with the boiler going into soft lockout. The pilot assembly was replaced under warranty and although that problem has not recurred, the boiler occasionally will show an Error 4 (low thermocouple amps) while running. I think this occurs mostly when the boiler is running to overcome thermostat setbacks.

After reading about temp setbacks here I have reduced them from 11 degrees (setback from 69 to 58) on all thermostats to the following for comfort:

Main house (occupied all day): 69-70 during the day, 65 overnight (9 hours).

Third floor bedroom: 69 morning and evening for about 2 hours each, 63 during the day (12 hours), 65 overnight (7 hours).

Third floor bathroom: acts as a timer to heat the floor continuously overnight with an off limit of 72-degree air temperature. Floor heat is off for 11 hours during the daytime unless the bedroom thermostat is calling for heat.

Greenhouse: 65 during the day and 50 overnight (13 hours-dictated by plant needs.)

I have been taking readings daily around 8 AM as much as possible and have observed the following:
In 2+ months the boiler has run for 318 hours, 3407 cycles. This averages to about 38 minutes between cycles and about 6 minutes of running time each cycle. However I have also observed that the boiler will sometimes come on for about 2 minutes, reach upper limit, and turn off for about 3 minutes and then cycle again. That usually happens when the main house is calling for heat and returning low temperature water (as low as 65 degrees in the return pipe but never below 100-degree boil temp) after a setback or during the day when solar gain and less heat loss have offset the need for heat. More recently as outside temperatures have been in the teens and 20s the averages have been closer to 5 minutes of firing in a 15-20 minute period.

For the month of November I ran with the following boiler settings:
HL = 181, dF = 30, Or = 0, PP = 5 minutes, St = 140. During that time the average morning outside temperature was 37 degrees (18 low, 58 high), average cycle time 53 minutes with average firing time of 6 minutes. I am attempting to extend the off time as much as possible to reduce short cycling. I did observe that occasionally the ODR was shutting the boiler off before reaching its HL due to warm outside temperatures.

I was able to get my contractor to have the Burnham rep call me to discuss the soft-lockout issue and I discussed my desire to extend the off time and the settings with him. (About the soft-lockout he also said that when the return water temp is very low, condensate might be falling onto the thermocouple.) The only other suggestion he had about the settings was to change the cycle time of my thermostats from the default of 5 per hour to 3 or fewer per hour. I chose not to do that because the thermostats do not directly control the boiler and I did not think changing their cycle times would have any effect. The thermostats control the zone pumps through a Taco relay box. The TT output of the Taco box in series with the ODR goes to the boiler TT connection. When the zone thermostat calls for heat the appropriate pump will start but the boiler will not see the call for heat unless the ODR allows it. If the thermostat and the ODR are both calling for heat the boiler will see that at the TT terminals but then will operate based on its temperature limit settings. The pre-purge would delay the firing of the boiler but so far the pre-purge has not done that since the boiler temperature is already below or drops below the minimum 140 degrees too quickly.

At the beginning of December, I reduced the HL to 171, since the boiler temperature sometimes went up to 196 (after firing ceases) with the HL set for 181. (I am using the 1-degree to indicate whether the boiler is restarting at 141 due to the 30-degree differential when actively cycling rather than the fixed minimum that will fire the boiler if the temperature has fallen below 140 during the time that no heat is being called for.) Based on the heat loss calcs and the radiation I thought originally that I might be able to run the system with a high limit as low as 140 but I think that may run the boiler too much in a condensing mode and that is not good for this boiler. I need to figure out the best high limit that I can coordinate with the ODR that will provide 100+ degree return from the distribution system and also avoid short cycling. I have observed the boiler temp as low as 128 when the boiler fires and I think that is due to it reaching the 30 degree differential (after having shut off at 158 because TT or ODR was satisfied?).

In December the average temperature was 27-degrees (6-degrees low, 49-degrees high), average cycle time of 25 minutes, average firing time 5 minutes.)
I hope this is the type of issue that can get you thinking. I think I have provided the kind of information (and not too much) that you usually ask for when someone posts a question here. If I have overlooked anything Im sure you will let me know.

I look forward to your comments and opinions about this and hope that others will gain some knowledge from your responses, too.

Thanks.
 
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Old 01-04-14, 03:23 PM
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The new gas ES2-5 is rated 140,000 BTUH input, 119,000 output. Three contractors independently selected that boiler size after visiting the site. No heat loss calculations were done.
Give them a pat on the back for installing a boiler twice as big as you need.

the water temperature sensor is not installed in the boiler but in the supply manifold
Rather than attempt to adjust the ODR (which is probably a futile effort), why not move the sensor to the proper location?

I hope this is the type of issue that can get you thinking
Me don't need anything to get me thinking! I can't turn it off!

OK, I read it all... have a pretty good picture in my mind... want to know what's in the greenhouse... no, don't tell me...

I'm not sure where to start at this point; how about some direct questions?
 
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Old 01-04-14, 04:11 PM
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Thanks for slogging through the narrative.

Is it possible? reasonable? likely? cost effective? that the burner(s) could be downsized to better match the load?

(BTW: I think my readings and calculations yesterday confirmed my heat loss calcs. We had 24 hours of 0-10 degrees temperature throughout the cloudy day and night and I calculated from gas usage that the boiler provided 72350 BTUH for that period.)

I don't see any ports on the boiler where the ODR bulb/well could be located. I would probably have to jury-rig something on the supply manifold at or near the pressure/gauge tap, or at the boiler drain tap.

The ODR may be a moot point since it may never be quick enough to match the quick response of the built-in boiler controls and the gas savings may be negligible. I'm going to override it in March when we are likely to have some warmer weather and see if it makes any noticeable difference.

Will letting the boiler run as it has been with 15-20 minutes cycles and 5 minute burn times adversely affect boiler or controls life or maintenance?

Is 171 a good high limit set point? With the differential set for 30-degrees it is providing sufficient and comfortable heat levels and the return temps seem to stay high enough to avoid condensing. If return temps of 107-158 (average 135) are adequate I would leave it at 171. If too low then I would try 175. Hight limit of 180 appears to be too much since it generates "soak" temps in the high 190s to low 200s.

Any ideas about how I can effectively use the pre-purge feature? Maybe my system volume is just too large. I think the boiler capacity is only about 3 gallons so there is not much residual available for my old cast iron rads and large pipe sizes and the boiler fires up immediately upon call for heat.

(200 orchids in the greenhouse-my wife's hobby. We lost them all 2 years ago in a freeze due to an air blockage in that zone so now we have a monitored low temp alarm in there. None of that Colorado stuff although the daytime grow lights do make people walking by wonder.) It's a nice place to sit and read in 65-degree, 50% humidity on cold winter days and watch the snow fly by.
 
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Old 01-04-14, 05:44 PM
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What is your total sq ft of EDR?
 
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Old 01-04-14, 06:28 PM
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EDR is 633 which I calculate can provide 125,120 BTUH with 150-degree water.

From what I have read on this forum and elsewhere those numbers don't really relate to the boiler output--heat loss is the key and the boiler is rated more than twice that.

Once I get the boiler running as efficiently as possible, I will have some questions about heating in specific rooms and emitter characteristics will come into play then.
 
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Old 01-05-14, 10:16 AM
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The number is important as it helps you set the high point of your ODR curve. Does that number include the copper fin tube and radiant floor outputs?
 
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Old 01-05-14, 12:14 PM
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Thanks.

Yes it includes the fin tube but not the radiant. The radiant was added for comfort level in small areas.

Here are the details:

Room Element Size
Zone 1:
Living Cast Iron 180
Foyer None
Dining/Kit Fin/Rad 12'+45
Radiant Approx. 35 s.f. under wood floor in kitchen work area
Family Cast Iron 60
Office None
Front BR Cast Iron 60
Rear BR Cast Iron 55
Bath Fintube 6
Z1 subtotal 418
Zone 2:
Greenhouse Fintube 90
Zone 3:
Master BR Fintube 68
Radiant Approx. 40 s.f under tile and backer board on insulated wood subfloor
 
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Old 01-05-14, 12:34 PM
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EDR is 633 which I calculate can provide 125,120 BTUH with 150-degree water.
I think you have you water temperature correct, but it will not yield 125,000 BTUH. More like 70,000 BTUH. http://www.comfort-calc.net/userfile...t_Emission.png


I think the first thing I would do is set the ES2 high limit to 150 because you will never need more than that. I don't know how to handle you existing ODR as I am only familiar with the ES2 ODR. I'm wondering if maybe you could use that for a system reset instead of a boiler reset. I would try to get the sensor moved closer to the boiler as NJTrooper suggests. I don't know how your piping was done, but I would try to get the sensor in a fitting that attaches to the supply that comes right out of the boiler. Right after where that gauge is.

You should take pictures of your system and show them to us. You can post them directly into the forum, but having them on a hosting site like flickr or photobucket would give us better quality images to view.
 
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Old 01-05-14, 03:52 PM
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Yep, for some reason I had entered the water temp instead of the BTU value into the calculations.

The ODR is definitely acting as a system reset in the current configuration.

Since my mixed supply temp into the system (after the bypass) is averaging low 140s I may actually bump the boiler HL to 176 for a while and observe the results. When I ran the boiler HL at 181 in November the mixed supply averaged in the upper 140s.

We had some really cold temps (near 0) last week and the greenhouse had trouble staying above its minimum overnight. Eventually I think I will have to repipe that zone to provide it with a higher supply temp than the system gets since it is 100% fin tube.

I will try to get some pictures posted tomorrow.
 
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Old 01-06-14, 02:46 PM
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Here are the photos. Assuming they load in the order that they are listed:
1. Top of boiler showing system return on left, bypass in front, and boiler return running to the back, left then down.
2. Front
3. Left side lower
4. Left side upper
5. Right side (Returns and pumps)
6. Supply manifold
7. ODR sensor at top of supply manifold
8. Supply closeup
9. DHW nipple on back of supply below bypass
 
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Old 01-18-14, 07:51 AM
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Oops!

In description of first picture, the system return is on the RIGHT. Sorry for the error and any confusion it might have caused.
 
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Old 04-04-14, 04:41 PM
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Whadda ya think?

Here is a summary of the performance this winter. Differential is set for 30 degrees and pre-purge is set for 10 minutes. ODR has little effect on boiler temp since the water sensor is in the system piping not in the boiler. It looks like setting the HL lower reduces the cycle time and the run time, but I question whether those are too low and will have a negative effect on boiler maintenance or life. Any suggestions will be appreciated.
 
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Old 04-04-14, 07:03 PM
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I think you should sell that over sized boiler and install a properly sized condensing boiler to take advantage of the low return water temperature . Just my opinion .
 
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Old 04-05-14, 08:22 AM
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Hmmmm... let's see... if one could even find a buyer for that boiler used... might get what, 25 cents on the dollar if lucky? and then what, another $8000 maybe for a new boiler... if you are lucky to find an installer that will work that cheap... to save how much?

Sounds like a very false economy to me.

I believe that new mod/con would be worn out in a scrap yard someplace before one could realize a savings from a move like that.
 
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Old 04-05-14, 08:24 AM
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John, how many SQ FT again? what does your B/D/S ( BTU / DD / SQFT ) come out to?

B/D/S allows direct comparison across fuel types and size of home... I'm running about 6.72 cumulative this season.
 

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Old 04-05-14, 08:30 AM
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I would nix the ODR.. I would set the boiler to the lowest temp to heat the home and forget it..If the green house is not heating you need to add more baseboard.

That es2 can have 110f return temps so no issue there. Additionally I would not set back the t stats either... If so maybe two degrees or so...

Thats probably the best you can do with what you have..

Just my opinion....
 
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Old 04-05-14, 08:41 AM
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A reasonable opinion, Saves, but not practical for me.

I considered a mod/con but decided for the atmospheric due to difficulty with the routing, location and appearance of the required venting, additional cost, and condensate drainage. The added cost and the potential saving seemed like a wash. My house was built in 1912, is historically significant, and the aesthetics of the venting just would not work with the style. I already had a SS chimney liner in place but if I knew then what I know now I might have considered it. I just saw recently on This Old House that there is a supply/vent system for high efficiency mod/con boilers that can be installed in an existing masonry chimney. Maybe next time.

I will just keep what I have for now. The savings over the old oil boiler are significant. Since November through March gas has cost me $1899.83 for 132.4 MBTU. Last year I spent $3000.20 for 707.2 gallons of oil (99.008 MBTU). Since this winter has been much colder I calculate that for 132.4 MBTU I would have spent $4009.03 for oil if it was available at the same price as last year. So I have saved 37% of the actual cost of oil last year or 53% of what it would have cost me for oil this year (or more taking price increases into account).

So at about $1100 per year savings I will break even on the cost of installing this boiler in 6 years. (Sooner if in take oil price increases into account.) Hopefully it will last that long even running at low capacity. I plan to have it serviced in June so if there any any issues they might be covered by the warranty.
 
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Old 04-05-14, 08:57 AM
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I was writing my reply to Saves when you guys chimed in.

I think from that reply you can see that I agree, changing now is not worth it.

The house is 2230 s.f. so the B/D/S appears to be running between 10.94 and 13.83. Certainly a lot higher than Troop's. But how does it compare to "normal"? I'm sure the greenhouse accounts for a large part of that.

I agree that the ODR is not doing much and I may decide to bypass it completely. (Easy to do since it was installed with a bypass switch.)

Setbacks have already been adjusted to a 3-5 degree reduction.

In the greenhouse I have installed a floor grille to provide more air flow over the fin tubes. It has improved the situation. And next summer I will have the insulation under the floor replaced.

Here's a new question. What is an acceptable temperature for the flue? Today I measured it at 159 degrees on the single wall connector at the chimney when the boiler temp was 154 (running) and the supply water temp was 161.
 
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Old 04-05-14, 05:21 PM
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Since my first suggestion is not possible I would encourage you to add a buffer tank to have a place to store the btu so that your burner can achieve burn times of 20 min. or longer. The old oil boiler would have been ideal , then the ODR could be better utilized . Remember for every 3 degree f system average water temperature is reduced during the heating season there is a 1% fuel savings . This 3 to 1 rule is taken from an article in the February 2013 issue titled Time For A Rethink page 33 . Another great article in the HPAC Sep./Oct.2012 is Onward & Downward by John Siegenthaler P.E.
 
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Old 04-05-14, 06:07 PM
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I just came across an article in the Sep. / Oct. 2013 Mechanical Business magazine page 46 Troubleshooting high temperature limits. The article states that a good heating system should be designed to have boilers cycle less than 1,000 times per heating season.
 
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Old 04-05-14, 06:36 PM
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If you are getting 10-14 minute run times I would be happy with that. As saves stated you could add a buffer tank or variable speed pump but don't think either will add to your savings that much.
Do you make domestic hot water with this boiler? If so you can get better run times by disabling priority. I will admit with cast iron radiation it may be more of a problem with having enough hot water, fin tubed baseboard it would not be a problem. My guess is it will be ok due to boiler being oversized.
Worst case you have to turn priority back on.
 
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Old 04-06-14, 02:56 PM
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rbeck, I think you may have misunderstood.

My run (burn) time averages 4 to 5 minutes. (metered therms * 100000 BTU/therm / input rating 140000 BTUH * 60 minutes / # of cycles)

The average time of heat call per cycle is 13 to 14 minutes. (measured time that TT is on)

The average cycle time in a 24 hour period is 22 to 31 minutes. (time between readings / #of cycles)

So on average in a 30 minute segment there is a 13 minute call for heat and the burner runs 5 minutes.

This is a gross simplification based on averages. The time between run cycles is much shorter during morning warmup from setback. There are very few calls for heat during the day due to solar gain and higher outside temperatures and the boiler goes cold. Radiant floor in bathroom is set to call for heat all night (so that accounts for 1 heat call cycle lasting 12 hours with a number of run cycles within it.)

Does this change your opinion?

I do not have DHW on the boiler--separate gas fired water heater.

As I said in an earlier post the savings I have already realized are significant and as much as I like tinkering to squeeze as much out of the system as I can, I may already be at the "good enough" point. I certainly have enough information and knowledge now to do it even better if there is a next time.
 
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Old 04-10-14, 04:55 PM
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Unhappy

So if you multiply your hours of operation x 60/ # cycles what does that come to? You are probably right it is as good as it gets.
I would try closing the bypass valve some. I think the layout here is reducing the flow through the boiler due to the bypass is straight and the return is off the elbow. Restricting flow through the bypass will increase flow through the boiler which will increase the boiler run time.
 
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Old 04-10-14, 05:50 PM
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rbeck,

So if you multiply your hours of operation x 60/ # cycles what does that come to?
That result is 5.5 minutes.

I tried tweaking the bypass valve one day in January. The return and boiler temps ran quite low but the run time per cycle went up to 7.6 minutes. I was not in a position to baby sit the boiler to monitor what was happening and the outside temps were in the teens so I did not want to push the issue at that time. I will try that again and see if I can find a good balance between run time/cycle, low return temp and minimum boiler temp of 100 degrees.

Thanks.
 
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Old 04-10-14, 06:26 PM
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In my opinion a burner run time is excessive cycling, which is hard on fuel and will shorten the life of the boiler components . I would be down sizing boiler or at least adding a buffer tank with a mixing valve and a Tekmar 360 to set temperature of supply water. This would improve burner on time and off time . The bigger the tank the more time the burner can run .
 
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Old 04-14-14, 01:27 PM
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Bypass closed: Good news! Bad news?

I have been running with the bypass fully closed for a couple of days. Seemed like a good time to try it since the weather has warmed up.

The result is burn times of about 12 minutes per cycle. One day had a heat call of 23 minutes per cycle and the other was 13 minutes. Since it was close to 70 degrees outside the ODR was also reducing the heat call time. Twelve minutes looks like a good burn time compared to the 5 minutes I get with the bypass open.

Now the bad news. Cold return temp and boiler temp. I checked a startup cycle to see the effect of cool return temp on the boiler temp. I assumed the worst case to be when the boiler is at HL from one of the smaller fin tube zones being on and the high volume cast iron zone at room temp (65-70) comes on.

From a cold start of the greenhouse fin tube zone (Boiler Temp 96, Return Temp 68) the temps rose to BT 130, RT 71 in about 70 seconds and I let it run until HL 155. I then shut off that zone and activated the main house cast iron zone. Temps were BT 160, RT 71. BT dropped to 91 when the circulator started and continued to drop to BT 88 (RT 79) by the time the gas fired up (10 seconds?). Continued to drop to BT 86, RT 79 while firing and then began to increase. Reached BT 100 in less than a minute and continued to increase to HL.

So which is more likely: shorter boiler life due to 5 minute runtimes, more short cycles and possibly higher gas usage, or possible failure from thermal shock with 12 minute runtimes, cool return temps and possibly less gas usage? I don't have enough comparative information yet to determine if there is any significant difference in Btu/DD or B/D/S.

Either way, as I said in an earlier post, I am saving 40% in annual heating costs and I anticipate about a 5 year break-even on this boiler.
 
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Old 04-14-14, 02:03 PM
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Fine tuning es2 boiler

To bad that boiler is not condensing with those return water temperatures efficiency would be in the high 90% . To protect that boiler your going to need a large buffer tank .
 
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Old 05-04-14, 05:12 PM
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Adjust the bypass to a happy medium. Remember that boiler will operate with a return temp of 110f within a reasonable time.
Properly installed there should be a valve on the return to control the flows through the boiler better. The valve in the bypass is not a good way to adjust and balance.
 
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Old 05-08-14, 12:15 PM
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End of season

The gas meter was read a couple of days ago and the heating system is effectively shut down for the season. The comfort level was excellent and the cost in line with what I expected. The chart below shows what it looked like.

Just to see what would happen I reduced the HL to 150 for the last few days. The bypass has been fully closed since the middle of April. I have shifted the ODR to its minimum curve (150 degrees at 10 degrees outside). I will start up with that configuration next fall and see how that goes.

Final savings of $1245 (38%) below actual 2013 costs--more if I calculated based on this winter being considerably colder than last.

Closing the bypass eliminates the need to change any piping this year but I will have the missing floor insulation replaced for the greenhouse and I am considering using the DHW terminal to control the greenhouse zone pump in such a way that if the greenhouse needs more heat I can drive the boiler temp higher while using the ODR to keep the water temp low for the other 2 zones.

Thanks for all your help and comments. Good luck with your summer projects.
 
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Old 12-19-14, 12:51 PM
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Update: New season--November results

Here's an update of how my ES-2 is operating.

Insulation under greenhouse floor was replaced last summer with 4 inch closed-cell spray foam.

As I anticipated in my last post I started the system at the beginning of November with a high limit of 150. After 5 days of good heating results (average outdoor temp = 49) I decided to reduce the HL to 140. I ran the remainder of the month at that HL with satisfactory heating.

Here are the stats for the month of November (11/5 to 12/4, 31 days):

Average daily outdoor temp: 40 degrees
Total monthly degree days: 776
Average daily cycle time: 40 minutes
Average daily Heat Call time/cycle: 22 minutes
Average daily Burn time/cycle: 7 minutes
Total monthly therms: 170
Total monthly cost: $247.35
Cost per therm: $1.45
Average B/D/S: 10

Compared to November 2013 (30 days):

Average daily outdoor temp: 40 degrees
Total monthly degree days: 626
Average daily cycle time: 53 minutes
Average daily Heat Call time/cycle: 11 minutes
Average daily Burn time/cycle: 8 minutes
Total monthly therms: 173
Total monthly cost: $247.08
Cost per therm: $1.43
Average B/D/S: 11

So for basically the same cost as last year (actually about $3 less) I used the same amount of gas in November this year that was 24% colder (150 more degree days) by running the boiler at 140 degrees HL. (If I adjust for the 1 day billing difference between the comparison months the numbers are 22% and 112 degree days.) Roughly $55 dollars less cost for the same amount of heat. I hope to be able to continue at that rate as the weather gets colder but time will tell.

The heat in the greenhouse is still a concern. See that thread at http://www.doityourself.com/forum/bo...more-heat.html.
The addition of the IQ ODR module and subsequent changes in settings may increase the cost of operating slightly because the HL set point will vary depending on which zone is in control of the heat call.

Also I have adjusted the third floor (MBR and bath) thermostat settings slightly. The room thermostat is set to come on an hour earlier in the evening to allow the room to reach 70 degrees by bedtime. Then it goes to 65 degree setback overnight. The bathroom floor thermostat has been set to go off at bedtime rather than run all night as previously programmed. It stays off for 5 hours then comes back on in time for the floor to heat up fully by the time I get up. This change has resulted in a reduction of the average total daily heat call from ~18 hours to 5.3 hours. There should be a slight savings due to reduced amount of time that the boiler will run at night. I don't expect that to be a lot of $ and if the floor cools down so much as to be uncomfortable for a nighttime bathroom break I will shorten the off time.

Your comments or questions will be appreciated. Otherwise, see you next month with a December update!
 
  #31  
Old 12-19-14, 05:32 PM
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Can you boil this all down to one or two specific questions?
 
  #32  
Old 12-19-14, 05:59 PM
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No questions in this one gilmorrie, just an update to last year's postings in case anyone is interested.

Thanks for asking.
 
  #33  
Old 01-09-15, 09:13 AM
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[B]Update: December results[/B]

Here are the stats for the month of December (12/5/14 to 1/6/15, 33 days):

Average daily outdoor temp: 33 degrees
Total monthly degree days: 1051
Average daily cycle time: 34 minutes
Average daily Heat Call time/cycle: 11 minutes
Average daily Burn time/cycle: 7 minutes
Total monthly therms: 234
Total monthly cost: $332.74
Cost per therm: $1.42
Average B/D/S: 10

Compared to December 2013 (33 days):

Average daily outdoor temp: 30 degrees
Total monthly degree days: 1153
Average daily cycle time: 25 minutes
Average daily Heat Call time/cycle: 17 minutes
Average daily Burn time/cycle: 6 minutes
Total monthly therms: 310
Total monthly cost: $437.22
Cost per therm: $1.41
Average B/D/S: 12

This December had 10% fewer degree days and after adjusting for that the gas cost was still $66 less this year.

The addition of the ODR module to provide hotter water to the greenhouse zone has not affected the overall performance or cost. Also the burn times increased to an average of 10 minutes per cycle in the second half of the month after I tweaked some of the settings. I expect that to continue.

Here is the system setup:

Zone 1 (cast iron) & Zone 3 (fin tube + radiant) call for heat on the ODR DWH terminals. DWH set point is 150 degrees.

Zone 2 (greenhouse fin tube) calls for heat on TT with ODR settings of Hb=180, Lb=135, Ho=65, Lo=-10. These settings increase the water temperature for the greenhouse above the 150 setting of the other zones when the outside temps drop below 40 degrees. In recent days we had temps near zero and the greenhouse held its minimum space temp of 52 overnight with 174 degree water set by the ODR.

I think I have reached the optimum settings for my situation and will be cutting back from the almost daily readings to weekly or less often.

Unless something really drastic or interesting occurs, this will be the last update on this topic but I will monitor the thread for questions or comments.

I hope it has been helpful.
 

Last edited by NJT; 01-09-15 at 10:41 AM.
  #34  
Old 01-09-15, 09:19 AM
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2john isn't this a typo, should be 2013:

Compared to December 2014 (33 days)
 
  #35  
Old 01-09-15, 09:43 AM
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You are correct it is a typo. It should read "December 2013". The gas bill came in January so I got confused with the year.

Thanks for pointing it out.

[edit NJT - I fixed the dates in the first post...]
 

Last edited by NJT; 01-09-15 at 10:41 AM.
  #36  
Old 05-14-15, 09:32 AM
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Final Annual Update--Tinkering paid off!!

Here are the final numbers for the 2014-15 heating season and the comparison to 2013-14:

2014-15
Total number of days: 182
Average daily outdoor temp: 32 degrees
Total degree days: 6281
Average daily cycle time: 59 minutes
Average daily Heat Call time/cycle: 13 minutes
Average daily Burn time/cycle: 8 minutes
Total therms: 1382
Total cost: $1,842.58
Cost per therm: $1.33
Average B/D/S: 9

2013-14
Total number of days: 183
Average daily outdoor temp: 35 degrees
Total degree days: 5268
Average daily cycle time: 45 minutes
Average daily Heat Call time/cycle: 14 minutes
Average daily Burn time/cycle: 7 minutes
Total therms: 1363
Total cost: $1,981.76
Cost per therm: $1.45
Average B/D/S: 11

Even though this year was colder with 1013 more degree days (+19%) the actual cost was $139.18 less (-7%). If I adjust for differences in days, degree days, therms, and cost per therm (i.e. if I assume this year ran the same as last year) the cost this year would have been $830.83 (+35%) more than last year.

The system settings remain the same as described 3 posts back (#33)

National Grid finally came through with the $225 rebate for the ODR so my out-of-pocket cost was $195--over 70% paid for by this year's actual savings.

Just as a matter of interest, from the 85 readings that I took during the heating season (mostly around 9 AM), the average set point for the year was 150 and the average boiler temperature was 134. The average BTUH loss was 65% of the calculated amount. Last year it averaged 75%.
 
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