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Help with Great Room heating strategy and the wrong thermostat
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Looks like you are headed in the right direction. I suspect you could flatten the curve a bit more (reduce the max SWT temp, but leave the min alone). With the boost function enabled eventually you could probably have your max set closer to 120F and allow the boost to take it higher if necessary. (Basically it adds some integral action to your set point instead of being purely proportional to OAT).schreib said:SuperJ: thanks for commenting!
Here are some comments and info that may give more perspective based on your input:
T'stat slab set points: 90°F hottest, Great room with biggest heat loss; 72, 79, 68, 70, 81, 78 these zones ALL control loop based on SLAB sensor except one-- uses remote air sensor. The one set at 72. SO, my water out to slabs in not very high.
Reset curve attached here;
My system pump automatically keeps flow the same by keeping the delta P the same regardless of # of loop valves open. Set now at max dP to control at 16 ft of head. Please note my posted files for delta T to see flows and dT's on all zones / loops.
I will look for the hidden flow adjusters and buy some thermal paste, thanks.0 -
Ramp delay 6 is what controls the final output. so if you put a limit % there it will keep it going. Now i see your sensor location. Your previous file didn't have the system sensor defined.0
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Thats not how it works on mine. I have 10f offset and 10 differential.SuperJ said:
Had a look at the manual:schreib said:Kalex: per note above, 10°F offset and 10°F differential;
Using 10F offset and 10F diff, will result in the boiler coming on right at setpoint, and shutting off when 10F over setpoint.
It works like this:
my ODR set point is 120. 10f offset will let the boiler's system temp get to 130 before it shuts down due to being blocked. Once it does that (it happens on mine often
) it then waits until supply temp drops to 110 before refiring. Differential is how low boiler temp can get from the setpoint before it fires up again and offset is how high the boiler system temp is allowed to get to before it gets blocked.
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SuperJ: You are using PID nomenclature-- Proportional, Integral, Derivative indicating to me, if Lochnivar TRULY has those algorithms in their firmware, that BOOST may be just what I have been looking for all along. I was complaining a bit back at the start that their control scheme does not even use 50 year old technology like PID. Calling them, it did not sound like they did, or if they did, the tech did not understand so . . Maybe BOOST could help me.
However, from what I have understood and "seen" of their anti-cycling parameters it does not use any kind of proportional control, just a ramp over time period. If you REALLY are saying Boost provides integral action and it really DOES, then that is great. To be sure we are on the same page re: PID controls, here is what I am talking about:
http://www.machinedesign.com/sensors/introduction-pid-control
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actually from what I learned and seen, lochinvar is pretty stupid at controlling itself0
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ha! ha! yeah, both the boiler and otherwise. I learned to get PID control over the reset curve I would have to use some Techmar board(instead of TACO's) that had a brain in it and use it with Lochinvar's external boiler mgmt setup to feed/ replace the boiler controls0
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You could do that. It does have Modbus/Bacnet (BMS) abilities but you need to get a board for it. I added it to mine but only for monitoring not controlling it.
Did you ever look at your DHW side? What do you have your boiler set to for dhw tank heating? 180/10?0 -
DHW tank is a squire 40 gal unit, set point is for 125°F, and I believe if temp falls 6 below set point it will kick in, take over priority from the Space heating.0
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sorry I meant to say what do you have your boiler set to? 180f supply with 10f offset to heat the squire tank?0
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If I recall the SH set point is 145°F and that same set point is used for the DHW, indisposed to answer further. . . !0
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You guys know better than me since you actually have the boiler:-) I was just referencing my interpretation of the manual (pg 20).
To me the default offset of 10 and diff of 20 will result in a 20deg wide band between start and stop centered on the target setpoint. But Schreib's approach of 10 and 10 creates a 10 deg band where the boiler will keep running but be at minimum fire since it's over setpoint which might be desirable to limit cycling.
I work in the building controls industry and agree the built in boiler controls function often end up producing some bad cycling behavior. We almost always control boilers using the BMS packages and directly modulate the boiler via a analogue input or a BACnet/Modbus interface. I typically start a boiler at minimum fire and hold it there for 30-60sec (after I get flame status) before enabling my PID targeting a SWT set point. I bias the PID up and down (Feed feed forward), based on RWT/flow rates, and may dynamically reset the proportional gain depending on flow rates. Most of the systems I work on these days are variable primary so boiler flow varies dramatically.
I was reading between the lines a bit and making some assumption about PID functionality in the Lochinvar boilers. To me the ramp limits appeared to be to rein in the whatever the algorithm is that comes up with the modulation percentage. I assumed there must be a some sort of PI algorithm under the hood. I suspect the "Modulation factor" on page 24, is actually letting you set up your proportional band (based on experience with other boilers). You may want to reduce it slightly and see what happens.
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I apologize. You are right. I just checked mine and differential is 20. and it is default so i never checked, just saw it happen when i was monitoring the boilerSuperJ said:You guys know better than me since you actually have the boiler:-) I was just referencing my interpretation of the manual (pg 20).
To me the default offset of 10 and diff of 20 will result in a 20deg wide band between start and stop centered on the target setpoint. But Schreib's approach of 10 and 10 creates a 10 deg band where the boiler will keep running but be at minimum fire since it's over setpoint which might be desirable to limit cycling.0 -
yep, same for me . . . I have not tweaked the two defaults. So, my description 10 F above set point if offset and 10F below ST PT(or -20F from offset level) is my differential.
SO, I am also learning from you that you were just using Proportional and integral as a means to describer, not truly as their controls meaning and that based on how the pros work(ie YOU) I should think again about getting the Techmar boards with the brains to do PID boiler control instead of futzing with this goofy anti-cycling ramp these bozos came up with. However, much of what you describe above in controls is beyond me, being I am a mere mechanical engineer and not a wizard controls guy. I will admit controls guys saved my bacon many a time! Handy guys to have around at machine startups!0 -
Nit picking thru the manual:
-I assume you've set the boiler to target the sensor you've installed on the secondary loop(P.25).
-Make sure the system pump is set to WWSD (warm weather shutdown) not CFH (call for heat). Some ECM pumps are fine to deadhead (they detect it and go into a low power mode and periodically check for an open valve by ramping up the RPM and measuring RPM/Torque).
-It looks like the boiler has support for a variable speed primary pump which is a nice feature if you had such a pump.
You might be able to be less aggressive with your ramp limiting (ie. allow it to go to 100% sooner) if you reduce your modulation factor.
My interpretation of the boost mode is not that it is a PID, but more of a trim and respond type function to optimize the setpoint. I would call it integral action but not in classical PID sense, since it uses fixed time and increment steps. In BAS systems we often program something that will slow step up the the boiler set point if a valve has modulated open more than a certain percent for a certain period of time. This is a similar function, lets you tune a efficiency minded reset curve without the worry of not having enough heat in prolonged cold.0 -
I'm a big fan of proper controls, but that being said I don't think boiler controls are at the root of your problem. The Lochinvar system seems adequate but maybe not nicely documented. Manufacturers seem to save the real tech training (where they might actually disclose what there black box is doing) for paying dealers and distributors.schreib said:yep, same for me . . . I have not tweaked the two defaults. So, my description 10 F above set point if offset and 10F below ST PT(or -20F from offset level) is my differential.
SO, I am also learning from you that you were just using Proportional and integral as a means to describer, not truly as their controls meaning and that based on how the pros work(ie YOU) I should think again about getting the Techmar boards with the brains to do PID boiler control instead of futzing with this goofy anti-cycling ramp these bozos came up with. However, much of what you describe above in controls is beyond me, being I am a mere mechanical engineer and not a wizard controls guy. I will admit controls guys saved my bacon many a time! Handy guys to have around at machine startups!
Get your flows and reset curve sorted out (then play with the boost mode and modulation factor) and then maybe consider adding the external controls next year.
I think your decision to upgrade the zone controls is a good one though. With high mass radiant heat you need some input from the slab temp or you get to far behind or ahead. Can you set a high slab temp limit too in your fancy zone controller on the great room? There are theoretical concerns about putting overly hot water into concrete, but I haven't ever actually seen damage.
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OK I will read over your points and check the parameters from boiler and get back. . . probably Weds. . . things are progressing rapidly here. . . ha! but yes, I agree with your points re: Lochinvar and waiting till next year. I should just say though, my brother designed my system; he is a rep for a boiler re-seller and he trains techs on Lochinvar's and other boilers they sell out of their Denver office. He told me also that Lochinvar, though he likes the boilers and recommended mine, seems lacking in controls application. I am hoping you can comment on my reset curve if you get a chance. My boiler loop pump is a 3 speed pump, manual set, and at the lowest speed presently.0
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In larger buildings we often setup the primary loop to have slightly more flow than the secondary. (But we have flow meters on everything and VSDs on all the pumps) This is to avoid diluting your sec SWT with RWT, which is what happens when your secondary flow exceeds your primary. When in this scenario your boiler has to supply water above the secondary set point since it will be diluted from the excess secondary flow.
Since you have a fixed speed pump (manual 3 speed), I would select the lowest speed that gives you forward flow (pri>sec) most of the time, and meets your boilers min flow requirements. (your boiler RWT would be slightly higher than sec RWT, but SWT will basically match). If the flows are close to the same, your boiler RWT/SWT will match your secondary RWT/SWT. At max load your secondary flow may exceed the primary, but since you are working at infloor temps the boiler will have lots of head room to make up the difference without running too hot. At min load the boiler RWT will be warmer than the sec RWT.
The key to efficiency with mod con boilers is keeping your RWT as low as possible. This means you don't want to over pump your primary loop. But you don't want so little primary flow that your boiler has to deliver 160F inorder to mix to 120F in your secondary. Many boilers have a maximum temp delta which you will run into if your primary flow is too low.
The Wilo pump running at constant pressure is a great setup for your secondary. It's simple and efficient even if you have to crank up the setpoint a bit, 16 ft of head isn't that much.
If your outdoor reset curve is forcing too hot of water at low loads your sec flow will be low, but primary will be the same as always (constant speed pump). This means your boiler RWT will be high (efficiency killer) since the secondary loop is only taking a portion of your primary flow (and the rest of the primary flow is actually going backwards between the tees and warming up the return). If your curve is setup properly your secondary flow wont vary that much throughout the year and your primary pump speed will be closer to ideal a much high percent of the time.
If your a tweaker, (which it sounds like your are), you may want to run the pump on low during the shoulder seasons, and switch it too medium/high when it's cold out (assuming your sec flow is high enough to warrant the change). It really depends on how much your secondary flows change with OAT.
Future upgrade could be a variable speed primary pump for a bit more efficiency. Note sure if this functionality is standard or requires some sort of BMS upgrade package.
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Regarding your reset curve, I would rather run more flow than higher temps if possible. 100F-120F is probably a normal concrete SWT (lower is often possible), and anything above 140F I would consider to be dangerously high for concrete.
Before going above 120F SWT, I would be double checking to make sure you don't have any dead loops (air locked), and that your flow is adequate. You might be able to detect dead circuits with an IR thermeter (or a FLIR camera). Walk around the room with a temp gun, and look for cold spots on the floor. There a bunch of people renting FLIR cameras on Kijiji in my area, might be worth trying to rent one for a day to confirm your floor, it amazing being able to see the heat in your floor.
Also, possible if you had a shifty contractor is debris in the system restricting flow. You sometimes need an external flush cart to generate enough pressure and flow velocity to get the debris out.
To purge your loops with your system pump:- Close all your zones but one
- Ensure you air separator vent is open
- Set circulator to maximum speed
- Valve off infloor circuits individually at manifold so all flow has to go to one circuit.
- Work your way thru the circuits one at a time to get the air out
- don't rush let each circuit run for a while on it's own
0 - Close all your zones but one
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It looks like I need to find a source for FLIR or a simple ir heat gun to check for dead spots. However, all my PEX is clear and I have not seen any bubbles coming by; system has been up and running over a year; and flow meters all indicate flow-- spreadsheets posted show flows. I am guessing you are saying, though, without actually checking for dead spots, even with OK flow, they may have air pockets only shown via FLIR, right?
Have you reviewed my spreadsheets on flow and loop delta T's and do you find any reason to be concerned about low flow?0 -
As long as the flow meter move to zero when disabled and indicate flow you may be ok. It's just that 140F is pretty hot for your application, so it might be worth double checking a FLIR image of your floor. You'll also be able to see the spacing of all the tubing.schreib said:It looks like I need to find a source for FLIR or a simple ir heat gun to check for dead spots. However, all my PEX is clear and I have not seen any bubbles coming by; system has been up and running over a year; and flow meters all indicate flow-- spreadsheets posted show flows. I am guessing you are saying, though, without actually checking for dead spots, even with OK flow, they may have air pockets only shown via FLIR, right?
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BTW, here is your balancing adjustment.
You use a key that should've come with the manifold.
I looked at the design documents you shared in your dropbox. It looks like the system was designed around 105F water, so assuming there is enough tubing the floor you must have a flow or insulation issue.
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Well, again about my reset curve. Top end really is 135°F to be exact and that is ONLY when OD temp is < -20°F. . . heck, even when zero outside the reset value is 122°F. (Usually, when below zero around here it is for hours at a time during night and then rising above zero during day. Worst scenario would include staying below zero more than a day continuously though. Also, not too worried about wrecking flooring, no hardwood floors(vinyl, cer. tile, and carpet) But, more to the point, the curve value has been totally unreachable under any condition I can throw at the system with the system pump running at high flow(9 to 16 ft hd setting). I can reduce that setting down to min(4 ft) and probably hit the reset value but at the expense of really slow response and high return temps and high loop delta T's. So, having come to a point where I am running system pump maxed out, and getting 10 to 20°F delta T's on the loops, it seems best to stay in that mode, right? I can have the reset curve as high as the sky but if actual performance to it is impossible(present setup) then it is only an "artificially" high reset curve. Do you get what I am trying to say? I suppose I could start stepping it down until performance(at this high flow) allows reset value to be met. . . What do you think of that plan? Also, once I get done with this "procedure" I will try to take the time to get Boiler setup parameters and compare boiler and secondary flows via temp comparisons you suggest. thanks.0
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I looked at your spreadsheets, it's hard to reach a conclusion since it's a high mass system. It does appear that you are moving enough heat to technically heat the room though based on the heat loss calcs. If a slab valve opens on a cold slab it may take hours for the SWT and RWT to stabilize once the slab is up to temp.
I would step it down till it achievable and keep the flow/pressure high. Looks like your garage is a major part of the heat load, so maybe keep that lower, to free up some extra BTU for the house.
If you change your balancing valve settings you may be able to reduce the pump setting.
Is it possible there might be some other problem with the great room (under insulated wall/ceiling/air leak/etc)? It seems not being able to achieve 70F space temp below 25F OAT points to a more major problem, especially since you're over design temp on the water already. The FLIR camera, if you can rent one might be eye opening for figuring out where that heat is going since you appear to be delivering more than the design amount of heat to the area.
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Thanks SuperJ, I will check out the manifolds but was never given "the key"! big surprise there with THIS contractor. I'm sure I could obtain one though. Another good reason to rent an FLIR . . . verify dead spots and confirm flow.0
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Yeah, I have not mentioned the garage because I have that out of commission. Garage is yet to be insulated up top on 2nd floor; Piping and all works but T'stat is turned off. Too late now this year anyway with it so cold-- fluid viscosity would just stop the pump dead.
OK I will follow through on reducing the reset curve until I can hit the values. . . good input! thanks.
What criteria , judge should I use to balance the flow? I am not SURE of the actual footage installed in any loop because I was not aware the contractor was not . . . er, good, truthful etc. So, it's hard to say I need any certain flow in any loop without knowing exact floor footage and piping length involved, right?
AS to Great Rm, I have no reason to believe any big "problems" other than the big windows, large footings on all four walls with no floor insulation under each one, large footing under fireplace no insulation. . . Other than that. . . my concrete contractor, another piece of work failed to put in the specified 1.5" x 5" foam barrier around slab edge. However, I still have 2" foam outside of found. wall down 2ft. More reason for FLIR.
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https://www.dropbox.com/sh/rmri2lut71smo3m/AAA2m77GNEQuTM9SXgm39CsAa?dl=0
Soooo, I asked the question about adjusting your loop flows, and you said you could not.......that’s an important element.
Been a while since you posted on this thread, and I didn’t go back 4 pages to recap.
I bumped your drop box link.0 -
yep, obvious from the manifold spec it DOES have adjustment.
I assumed wrongly that without a ball valve there was no adjustment. All my return manifolds have the solenoid valve mounted on top and I was not aware of how the actuator can be removed, key adjustment made, and re-installed. I will have to get a key though.0 -
I hope your procedure goes well today.
One thing I noticed on your spreadsheets was that your circuit inlet temperatures were up to 10F below the boiler SWT. I would probably bump your primary pump from low to medium speed to compensate for the increased flow from secondary pump being set to a higher pressure setting. Since your boiler is at 100F anyways this likely won't make much of a difference, but I think 10F might be a bit more spread than is ideal.
Another thing would be to set your DHW temps up in a way to minimize interruptions to your system heating calls. (probably hot with a big differential). There are also some DHW pump delays to check.0 -
thanks SuperJ, procedure went well, negative findings! Real hungry after though.
You provide a few data points, settings that will take me a bit to check on.
I will review it all tomorrow, pretty tired now. I need to make sure the data you referenced etc. matches with your recommendations. . . could be a trip up here if i assume one thing and you mean another. . . thanks again!0 -
A simple 50 dollar infrared thermometer will suffice just fine.
Get your loop flow rates dialed in. The higher delta loops need more flow.
You need to get the system tuned before you fiddle with the boiler. Otherwise it’s counter intuitive.
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Agree with Gordy to start with balancing. On a high mass system, short term fluctuations in temp from the boiler shouldn't really be affecting comfort too much.
You may be able to improvise something if you don't have the key (eg. careful use of needle nose pliers).
When balancing you want to make sure your highest pressure drop circuit is wide open, or you will be wasting pump energy. In other words it's better to have less restrictive balancing valves and run at lower pump pressure than have everything closed off and your pump cranked way up.
About the FLIR, you can rent one for pretty cheap. But they are prohibitively expensive to buy (there is a nice smartphone compatible one for less $$$ since it doesn't have a screen). It will help you verify your contractor's work since you should be able to get an idea on the linear length and spacing of your infloor circuits.
Example: https://www.kijiji.ca/v-electronics/city-of-toronto/flir-thermal-imaging-infrared-camera-for-rent/1328309000?enableSearchNavigationFlag=true
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OK, thanks Gentlemen. I will rent / get FLIR or std IR meter, get a key, and do this. Like I said, since I did not get lineal feet readings on the loop lengths from contractor I will have to use some common sense to determine which has highest dP . . . Based on flows I have seen I will be sure the Great rm, of course, has no restriction / balance valve is fully open, first. Then, I have 2 zones where I keep the temp low always since little used: dining rm and Guest suite; I will limit them to min next. . . then start from there. I will also get back with a full list of boiler settings soon. Lots are defaults already.
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You also mentioned that you have a carpet. From what i read carpets are bad for radiant floors. have you tried removing it to see if its better?
Also as far as DHW - You should set the boiler output to 185f with offset of 10f from your 145. you want the tank to heat up as fast as possible and switch back to Space heating. I and others noticed that if you leave it on default 180f supply with 10f offset your boiler will cycle on DHW. 185f /10f offset works the best as boiler modulates down properly. After i switched mine to that setting, I know get one cycle runs instead of short cycling1 -
Thanks for input Kalex.
Yes, I also pointed out that I am planning to at least remove the carpet just adjacent to windows to enable a bit more output near the biggest heat sink in the room, about 2 ft x 20 ft. I have a pair of 500watt baseboard heaters, yet to install, on same wall to augment the heat feed / loss from all the windows. FIRST, I must convince wife to ALLOW me to do that!
As to DHW: it must be that with particular settings I have there is no cycling at all on DHW. It satisfies quickly(minutes after shower) and never comes back to DHW while handling the SH. I don't understand your statement: "set the boiler output to 185f with offset of 10f from your 145". I could set DHW set point to 185 with offset of 10°F, which would mean it would allow DHW sensor to hit 195°F max before shutting down, no problem. but am confused why you mention 145. . . Must not understand something. I will verify my parameters, list them, and then we can continue this bit. . .
Meantime: Right now, my Squire hot water tank set point IS 125°F, not 145 or higher. My reasoning for choosing this is simple but perhaps naive. I have heard rumblings that higher temp may be necessary to prevent bacterial growth. . . some ref above, cannot recall. Any thoughts on that, why I should not keep it at 125°F for simple energy reasons?0 -
FLIR: After reviewing present market on line and the fact that it will cost me $55 to rent one at Home Depot, I bought this one from Amazon:
https://www.amazon.com/dp/B071Z63RSL/ref=sxbs_sxwds-stvp_2?pf_rd_m=ATVPDKIKX0DER&pf_rd_p=3341940462&pd_rd_wg=6ohdB&pf_rd_r=3YRPX5Z9MCTTM7ZBTTV0&pf_rd_s=desktop-sx-bottom-slot&pf_rd_t=301&pd_rd_i=B071Z63RSL&pd_rd_w=U5qnW&pf_rd_i=thermal+imaging+iphone&pd_rd_r=df3ec691-e0d4-474b-b354-bb2a0306746b&ie=UTF8&qid=1519833965&sr=2#customerReviews
I heard enough downsides to a simple thermal camera to not want one of those. You get so much more for $190 and then can resell it for at least $100 later if you want!1 -
You might have some tough questions for your contractors once you spend some time with your new toy. :-)1
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Actually, I paid a bit more and got lots more resolution:
https://www.amazon.com/gp/product/B00NYWABAA/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=10 -
gave up on the heating contractor. . . if you read some of the earliest comments. . . you'll see why! Learned a hard lesson, should have engaged his competitor; Aune Heating. I will take the time(and have the time) to do it "right" on my own. . . retired.
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