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Help with Great Room heating strategy and the wrong thermostat
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Oh, well sure, I do agree. That's why I plan to wait 3 days more to take a second set before reporting it to the Sergeant-Major. I am just saying that to use the strategy of using boiler for main control and T'stats as a top off, I must get control of the boiler.. Getting control of the primary loop, at THIS time, seems "difficult". Maybe after things settle out, you must be affirming, we can expect the boiler to reach set points of the reset curve without requiring anti-cycling ramp control. Hope so.
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> @Gordy said:
> Thermo equilibrium can take days to reach in high mass systems. So running around changing multiple variables before they have a chance to give full effect can get you chasing your tail. Follow me?
This. It's going to take a while to tweak things in. Luckily you are a homeowner who is willing, and able, to do this. The people getting burned on these systems are the ones who don't even realize the boilers aren't adjusted right. The only way to get max efficiency out of a mod con is to have it adjusted so that modulation and low return temps occur. And with a slab, it could take days to reach a steady temp. But once it's there, you should only need to dump the Btus you're losing to outside, back into the slab.
Don't worry, you'll get it figured out!0 -
Sergeant- major?......okay........ Let's wait and see what happens.
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Yes sir, Sergeant-Major! 0
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It took a while but I got some flow & dT numbers. See two files. One is for high flow setting and 2nd is Max flow of the distribution pump. Max setting is 16 ft of head it works to maintain that dP across the pump regardless of pipe circuits open to pump through. I tried to do data taking early in morning with the boiler and stats setup to answer demand of at least 3 or 4 zones and boiler running at 100% output. The reason for this post is to provide info on the system to provide the lowest dT-- max flow forces this. Looking for input on what else I need to do or are these dT levels close enough? thanks!0
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Before I comment, are you happy with performance one flow verses the other?0
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I’ll assume as to being an engineer the wide variation in some of the deltas Is driving you insane.0
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Gordy, I assume you are asking about the comparison of flows from the one data sheet to the other. The difference is 3 ft of head-- one sheet is for Wylo pump head set at 13, the max is 16 for 2nd sheet; as now set. I am fine with performance of both but would set it back to 13 ft head point simply to use a bit less electricity. I personally see no advantage to running at the max flow vs the 13ft. I maxed it out only to show you what the best potential is for attaining lowest delta T.0
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By the way, the boiler has NEVER even come close to hitting the Reset Demand curve's set point in conditions of 100% demand with multiple zones "on". Once the demand drops off so only, say, 2 zones are in demand, then it is able to hit the set point required of the reset curve. (I am referring to what Lochinvar calls the "system" temperature not being able to reach the curve's set point to be clear. For example, if the curve shows the set point to be 130°F, the boiler shows "system" temp and it is usually 10°F or more shy of that.)0
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If the system reaches setpoint before ODR target temp is reached the curve could be to high.
Under What conditions is this happening? Are you setting back? How many is multiple zones?0 -
Not using setback. It happens whenever the ODT is really low, say < 10°F. Multiple zones usual means 3 or 4 max. I have never seen the demand for more than 4 zones at one time.
However, your statement: "If the system reaches setpoint before ODR target temp is reached the curve could be to high." makes me wonder if my understanding of the controls and yours is different. I infer here that you believe there is an ability to set a value for set point independent of the reset curve.
The way I understand the Lochinvar setup and naming convention is that the SYSTEM TEMP is that of the SUPPLY fluid going out to the loops and the ONLY set point IS the reset curve equation value-- inversely proportional to the OD temp. There is NO set point other than that dictated by the equation of the reset curve. So, when I say "has NEVER even come close to hitting the Reset Demand curve's set point" I mean that the system's supply fluid to loops, (SYSTEM) temp, is not capable of reaching what the control algorithm /reset equation is using for the set point at that ODT-- boiler @ 100%.
TO ME this simply means that the demand is so high even with the boiler running at 100% output it cannot transfer heat fast enough due to the WYLO "system" pump rate. So, the heat transfer at the short spaced T's is not efficient enough and the heat output of the boiler loop is not high enough to enable meeting the 2ndary loop set point(of reset curve). I don't regard this is bad, and my conclusion is the same as yours: the reset curve is too high. However, does that really matter? It simply means the boiler will run to full output and try to meet demand and if it can't, it can't. I could tweak it down to a new level but that will not change the end performance. Within a half hour usually the thermostat is satisfied, it drops out the demand for one or more zones, less fluid is pumped requiring lower heat transfer, so then the reset curve set point can be and is met.
I am still interested in your input on the delta T's. Basically, the max flow spreadsheet says it is as low as I can get with pump I have. Still not down to the level of 10°F which, as I recall, you wanted to see. Comments on that? thanks!0 -
When I say set point I mean the desired room temperature. If that is reached before the ODR supply water temperature is reached.
Delta the higher delta ts in rouge loops can mean many different things.
Longer loop.
Zone that has been setback for a long period.
Higher heat loss in the area that loop covers.
Flow rate to low for above factors.
Maybe the higher delta loops are along an exterior wall?
Looking at your return temps that boiler is running high efficiencies. I’d be happy with that.
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The 10 degree delta for radiant floor panels is a design criteria. Could be more, could be less it depends. The deviation can depend on many factors in my previous post. The 10 is mostly for comfort across the panel, and panel output.
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Thanks Gordy for all your input! OK, so you just meant thermostat set point for a zone, not boiler output set point. I figured it must have been something simple!
All zones have exterior walls involved but the two zones with large delta T's have the most lineal exterior footage. Good call.
Ideally, it appears you would like to still see approx 10°F delta T, and just guessing here, if I had ability to individually throttle flow to some and increase flow to those with larger delta T, you would go with that, right? (I do not have that ability though.)0 -
I was not aware of this design criteria. Can you tell me where this 10°F shows up? Tech training courses? specific books on radiant panel design? thanks again.0
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Radiant panel design.
Floors 10
Ceilings, and walls 15
Baseboards 20
Radiators 20-30
Longer loops, and loops covering exterior walls with higher heat loss will have higher deltas which can only be narrowed by higher flow rates.
Having the ability to individually control flow rates to loops is a benefit. Your manifolds have flow meters for the loops, but no flow control devices on the manifolds for each loop?0 -
System temp not reaching desired temp from outdoor reset is weird. Where is your system sensor located?0
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Yes, correct no way to throttle any individual loop. There is a few inches of PEX sticking out of the floor before hitting the manifolds though. I suppose a really small throttling valve could be inserted. . . ? However, with the Wylo pump regulating the pressure drop it circumvents trying that. It will just keep the head the same(flow effectively) regardless on how much I throttle the other zones. . .0
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"System temp not reaching desired temp from outdoor reset is weird. Where is your system sensor located?" kalex
Lochinvar specifies it to be placed at outlet from SUPPLY distribution pump. It is placed after that pump and just before the feed T supplying all loops. Boiler is Knight WH55. One supply pump(WYLO ECO self regulating head control), one DHW pump for a Squire tank w/ DHW priority, and one Boiler loop pump. Simple short spaced T's to exchange heat between loops.0 -
Some thoughts.
You are using a slab sensor, and ODR.
The supply temp in the primary loop (boiler) is reaching target temp for ODR?
The system (secondary) loop is not reaching ODR target temp.
Have you tried just disabling slab sensor, and using t stat air sensor with Outdoor reset?
Technically the slab sensor just stops flow to the zone if it over heats. Same as air sensing except the slab sensor keeps the mass in check before it has a chance to fly wheel, and over heat the zone it’s controlling .
What is the delta t in the primary (boiler loop) during these operations?
Remember system flow rate must be equal to, or greater than boiler flow rate. With a modulating condensing boiler to reap the highest possible efficiencies.
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Response in order:
-- 7 of 8 loops use slab sensor, in fact, I did disable one: the Kitchen uses air sensor because slab sensor located wrong by contractor. I bought a remote sensor for that. The individual thermostats ALL eventually reach set point, even the kitchen with the remote air stat. But they are not slaved to the reset temp. Their outputs go to TACO boards tripping solenoid valves to open the Supply to those zones at the supply manifolds. I do not really understand how to use the outdoor reset function on the Lochinvar to modulate the thermostats. I do not BELIEVE(??) that is possible with my controls as they are. Wouldn't I have to feed the stat with the reset equation? Those parameters are setup in the Boiler with no connection to any stats.
-- I think I now know where you are going with this: "slab sensor just stops flow to the zone if it over heats". I was able to circumvent that: so, No, by some unique programming I have been able to actually use the slab sensors to do closed loop control of each loop. The downside is in the Great Room where I need MORE than the top end control of the loop above 90°F. That zone just barely is able to keep the zone hot enough on the worst days. I could buy a Tekmar stat and get higher top end control but am living with it for now.
-- Yes, system temp not hitting ODR equation value(temp) when boiler putting out 100% and 3 or more zones running. With less demand from various thermostats / zones it easily reaches the ODR value. The boiler was putting out 100% when I took readings and so the boiler / primary loop is maxed out, I assume. I also assume that the boiler loop exit sensor (in the boiler) is being reached but do not understand it's real character. (Is it only a high level control to prevent overheating?) However, the system sensor mounted on the 2ndary loop is the feedback to the boiler for reset equation control as I understand things. So, essentially, the boiler can be running full tilt and the Reset value be, say 125°F, low temp outside, but the 2ndary loop "system" value displayed on the boiler will be 5 to 15°F lower-- depending on how many zones demanding.
-- I will have to wait till tomorrow morning to check boiler loop delta T when in high demand.0 -
This afternoon: delta T is only around 7°F across boiler loop with 2 small zones demanding; about 30°F outside.
I should point out that when the boiler is in low demand(say just one or two zones with temps above 20°F) it has just the opposite character: the system temp consistently EXCEEDS the reset value set point. In fact, so much so that I am forced to utilize the primitive anti-cycling algorithm lochinvar offers to prevent undue oscillations and eventual boiler shutdown because it hits 10°F over set point.
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Thermostats do not do anything for modulation and ODR. ODR just sets the supply temp based on outdoor temp
Something is off.
I just checked my lochinvar and its currently running at 10% modulation and system temp matches up with outdoor reset temp. My system sensor is right after the main pump on my system. Can you post the picture of the sensor location and how its connected? is it in the well or if its on the pipe is it insulated?
Here is a screenshot of my boiler screen
Also same details from conxus ipad app
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I agree with Kalex1114. Something isn't set right. Your system temp shouldn't be exceeding the outdoor reset temp, at least not by much. I have a WHN055 and it won't go more than a few degrees above outdoor reset temp. Take a look at the picture I attached. In the pic, the boiler is trying to modulate down further than it can, to meet the reset temp. (The WHN055, min modulation is 20%, 1:5)
In the "control modes" parameters, are you sure that you have "out/sys" selected as the controlling sensor? It won't use the outdoor sensor if not picked.0 -
Schreib, I don't think you ever posted pictures of your boiler and near boiler piping. Consider taking some pictures from a few feet away and at different angles and post them here. Maybe there's a simple piping error somewhere. (And we like pictures.)☺0
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> @RxRoy said:
> Take a look at the picture I attached. In the pic, the boiler is trying to modulate down further than it can, to meet the reset temp. (The WHN055, min modulation is 20%, 1:5)
@RxRoy what is your dhw tank differential set to? It shows set point of 145 and tank is at 133 and it’s now running dwh mode.0 -
I'd have to check. I think I have it set to fire DHW at 130, shut off at 145. In the picture it's not firing DHW--my second zone (bedrooms) is running. It would show "DHW" at the top (where the house with the 2 in it is, in the pic), when heating up the indirect. And it would be running at 100% or close to, when heating the indirect. My average cycle time for the indirect is 26 minutes, and it only modulates down a bit at the very end of the cycle.
My goal is to fire the indirect as infrequently as possible, because it's not as efficient as space heating, due to the supply temps needed (and non-condensing flue temps). By heating to 145, I avoid the bacteria issue. By cutting in at 130 I avoid overcycling. I see no reason to try to keep the indirect temp right at my set point. Let it wander a bit, keeps the boiler from cycling needlessly. I mix down anyway.0 -
Ah sorry I meant to say not running instead of now running
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Makes sense. My tank sensor is at the bottom of the tank so by the time it gets to 130 and satisfies the call, tank will coast to 145 on its own. I also mix it down to 120. My differential is 5f so it fires at 125 gets to 130 then coasts to 1450
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Something is not right. Could you post some pics of the near boiler piping.
I really don’t know how system side temps could exceed primary side.........
Could be a bad system sensor, or how it is placed, and, or attached to the piping. Strap on, or well sensor?
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Kalex: " I have a WHN055 and it won't go more than a few degrees above outdoor reset temp." Mine does the same on low end. No problem reaching and maintaining Reset set point temp usually, but the parameter is set for +10°F over before boiler is shutdown to 0%. My WH55 cannot modulate below 20%
RxRoy: I guess you are agreeing with me then that the thermostats have nothing to do with reset etc. . .
Gordy, Kalex, RxRoy: Boiler is piped according to Lochinvar manual. (Was NOT originally but I prevailed with Contractor. He did not even want to install the ODR sensor, I had to. moron.) I gave up trying to get him to install the system sensor in the provided well. He installed sensor by strapping to the pipe and using simple foam pipe insulation around it to prevent heat loss there. It DOES seem to "work" ok and I have had others also tell me that the well is not necessary. As a mech. engineer my input on that is that the temp sensor will simply see a delayed response as compared to if it was in the well itself, but it will follow the temp up and down pretty accurately. It may simply be always low by a degree or two and lag in time a few seconds.
Kalex and RxRoy: I do not believe anything is piped incorrectly. (I will put a piping diagram up.) Jan 4 I posted diagram but it was not quite "right". Images were not able to capture the piping because various items obscure the piping. Diagram is better. The system sensor is selected to be used; I assure you.
As to System temp exceeding the Reset value temp: my settings are to allow a 10°F system overshoot past set point(Reset value) before the boiler shuts down entirely to 0% output. This happens with low demand and then it takes a couple minutes for system temp to hit 10°F below set point before the boiler is kicked in again. Typically, this action continues and the boiler will cycle on / off -- unless I engage the anti-cycling algorithm. This never happens when boiler has high demand and cannot satisfy it-- @100% output w/ 4 zones ON, low ODT.
As long as I have anti-cycling ON its effect is:
-- LOW demand to slow down the rise in boiler output % to prevent boiler overfiring to the extent it goes beyond the 10°F parameter;
-- HIGH demand it simply takes a LONG time to get to 100%, basically slowing response to outside temps.0 -
I did not realize there are 3 "pages" of comments and DID find previous files I posted-- images of piping, diagram etc. Back on 1st page of this post they can be found. Noticed the pg 45 from manual of piping does not show the close spaced T's for heat exchange. I will post my own diagram, very close to that one.0
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WHN55 is only 5:1 turndown so yes it can't go below 20%. 10f parameter you are talking about is an offset. there is also differential setting which is how much temp drops below setpoint for the boiler to kick in again. What anticycling ON setting are you talking about? there are 2 ways to control it. Delay in minutes, and differential of water temp below set point. I'm not aware of anything else that controls it. Can you post your lochinvar settings?
easy way of doing it is to get the service manual:
http://www.lochinvar.com/_linefiles/1000288296_2000546130_SERVICE MANUAL_WH56-WH400_Rev A.pdf
page 15-18 have all the settings available. just write down what you have vs original and post them. something is off. My KHN never has an issue reaching setpoint. it has other issues but never to reach set point.
Also posting pictures of actual piping is better than diagrams. Can you post them?0 -
Kalex: per note above, 10°F offset and 10°F differential; I failed to use the Lochinvar nomenclature.
I have all the manuals, will run thru all relevant parameters and post as you suggest. I have a program for the anti-cycling that includes ramp % and time for each ramp, will post. I have posted the reset equation on Jan 4, I believe. Please page back to find. Sorry, you will just have to believe me, pics will be no good. I will make a GOOD diagram, readable by all. My system has problem reaching set point ONLY under high demand and VERY low temps outside. What is lowest temp YOU ever see in your area? Things have been in minus zero for six weeks here on / off.0 -
two checks on boiler delta T(primary loop):
-- 78% output-- 15°F
-- 100% output-- 15°F0 -
ah so you are using ramp delay as well. are you limiting location 6 in ramp delay settings? Can you get to temp if you disable ramp delay?
What are the 2 checks you posted?
My temps are not as low as yours. Lowest it was was about 5 degrees with realfeel of -10-20f for 2 weeks. Also didn't have an issue getting system temp to whatever boiler called for. I did have to increase my low temp curve a bit but only because my master suite can't get to temp i was looking for.0 -
I would put some thermal paste on the sensor if it's a strap on. (kinda like a fillet weld). Then wrap the sensor and pipe in the stretchy foam tape to avoid letting any air flow over the sensor. But on low mass boilers I think sensor wells are worth it.
I read most of this thread, one thing that I don't think has been mentioned is that the target delta really only applies at the design SWT. If you run hotter water in the slab you the slab will emit more BTU/sqft and thus run a higher delta at the design flow rate (assuming the space temp is constant). When it's warm out and your water is only 90-95F you may be running a lower delta than design since your water temp is close to room temp.
You want to tune your reset curve to keep your floor valves open as long as possible without having the room temps get uncomfortably cold. When your valves satisfy and close the high heat loss areas (near outside walls) will cool off faster (less comfortable). So in other words: better to run 110F deg water with the valve open 80-95% of the time, than 125 with the valve open 50% of the time. The method mentioned to use the space sensors as a high limit would accomplish this nicely, but would demand you dialed your reset curve in nicely to avoid overheating.
With high mass infloor it's ok if your boiler is off for a while even if the temperature drops well below setpoint due to whatever anti-cycle differentials and time delays you have setup. With lower SWT setpoints the flow rate will be higher which may translate into longer runtimes closer to setpoint, instead of short cycling and overshooting at low flow/high temp.
Some manifold systems have "hidden" flow adjusters. Not sure what manifold brand/model you're using but if it has flow meters it probably has flow adjustment. You sometimes have to remove the cap or circuit valve to get to the adjustment.
It sounds like you installer tightened up the spacing near outside walls to 4 inches, if so that good. If it's just random 4inch spacing where he was lazy then no benefit.
Pure subjectivity here but I would limit the top end of your reset curve to 110F-120F and then work downwards (or more truthfully I would start low and work up, but your already high) assuming your flow rates a dialed in to design flows.0 -
Kalex: in order. . .
the latest Ramp Settings: always use delay, I don't see how this can work without a time for the rated %.
#-- minutes-- %
1-- 3min-- 25%
2-- 5 -- 45
3 -- 20 -- 70
4 -- 20 -- 85
5 -- 20 -- 100
6 -- 20 -- 100
always get to temp, except in really cold weather,
Checks, as described above were to answer Gordy's question for what is the delta T across the boiler, primary loop. So, there is a 15°F difference between the incoming fluid and exit fluid across the boiler. See posted, diagram also.
The diff between my home and yours is likely that with REALLY cold weather and lots of fluid to transfer heat being pumped it is a bigger demand than what the boiler can "immediately" handle while running at 100% output trying to hit the set point of the reset equation with system sensor temp. So, I have to wait a half hour or so before enough return loop water is warmed to the point where the return is able to be heated to what the system sensor requires for MY particular reset curve. Also, my reset curve is higher than attainable by the boiler. No problem there, but I did so to not limit the boiler from maximizing its output. Earlier I had a lower curve and the boiler could easily hit the demand required to be at reset value(like yours). BUT, I have a zone with lots of big windows, cathedral ceiling, carpeted that has a much higher demand and was not able to be satisfied even at 10 or 20°F outside. SO, that is why I was initially on the forum here to see what I could do to tweak things:
-- move up the reset curve to force set points up across range of ODT's.
-- increase the flow rate on my system pump to minimize the delta T on all the loops. (now 10 to 20°F)
-- change t'stat in Great Rm to another brand that will allow me to run high end of stat beyond the 90°F limit of Pro One(Techmar, not yet done)
-- put a couple of baseboard heaters under the windows,not yet done
-- remove some carpet and put thin flooring adjacent to windows.
SO, I learned a lot and think I am pretty happy with all those who, like yourself, have pointed things out I may have missed. SO, thanks again!
See diagram attached.0 -
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.
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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.
I think you should either:- reduce you offset to 5F (so the control band straddles your setpoint). Will start below 5F below setpoint and stop when 5F over setpoint.
- OR, increase the differential to 15F so that the boiler doesn't start until it's at least 5F below setpoint. (it will still run until the setpoint + offset of 10F above setpoint.
Anti-Cycling is basically a min off time, with high mass infloor. I don't see why you shouldn't set this to 10 minutes, with a 10deg F differential override (delay is overridden if the temp drops this amount below set point). Keep in mind the goal is smooth space temps, not water temps. A 10min blip off below set point won't be detectable in the space, but will save efficiency killing boiler short cycles, and wear tear. Seems like a good arrow to have your quiver when tuning.
The ramp settings aren't meant to replace good PID control, it's more to protect the boiler in a over-sized boiler/low load scenario. (think of it as a limit or safety, not as the primary control) The PID may crank up the boiler too quick and result in short cycles on low loads. You really want to keep the boiler running, even if it means undershooting initially by a bit. The ramp lets you tune this. It may be tough to look at a undershooting boiler and leave it along if you have OCD, but I would much rather have a boiler take 10-15 minutes to get to set point and modulate smoothly, than have it come blasting on and cycle 4 or 5 times an hour.
0 - reduce you offset to 5F (so the control band straddles your setpoint). Will start below 5F below setpoint and stop when 5F over setpoint.
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