Lochinvar Knight MRHL Lockout

Vinny_5

I've been experimenting

the last couple of days, lowering the setpoints each day and have now got the 2 zones down at 140*, again with no comfort issues at all.  It went down to 26* outside in my neck of the woods this morning, but the house is at a comfortable 70* all day, and even at the furthest point away from the boiler as well, which is where I thought it may be negatively affected.  It's currently 42* outside as I write this and comfort is even and constant throughout the house. I will try this for a bit and see how it goes, and if I am correct, I should see even more savings since the return water is in the 120-140 range.  I keep checking on the boiler when I hear it call for heat, and much of the time it's at 20% modulation now. I want to see what that relates to at the end of the month when the bill comes in.  I know it's been extremely mild this winter, although we did see one 0*F day this January, and the coldest I remember it being here was about -10*F or -15*F or so a few years ago, but over 50% of the winter we are above freezing, so I may be able to keep it at these settings next winter.  

Vinny.

Zman

Outdoor reset

What are the settings that I mentioned in a previous post. Changing the setpoints does not change the curve. It just flattens the top if it.

Vinny_5

I fiddled with the outdoor reset numbers as well.....

OK, outdoor low temperature is now set at 10* (we have had one 0*F day this year and maybe it should be set even lower but I don't expect it to get that cold again before this heating season is over), outdoor high is at 70*, setpoint @ low outdoor temp is 160*, setpoint at high outdor temp is 70*, outdoor shutdown is at 68*,  shutdown differentials at 10*.

Also, the 2 SH 1 & 2 setpoints are at 140*, with a min. setpoint of 100*, and max set at 160*, and offsets now set at 20*, so it will allow it to overshoot the 140* mark to 160* to satisfy demand on a really cold night but not coming close to a lockout MRHL ever again.  (at least that's what I believe to be true) 

It was 20* here last night and I was concerned that it may get a little uncomfortable, but it was just perfect.  I have been checking the boiler quite often now and when there is a call for heat it ramps up to around the 140* setpoint, and then it ramps back and mostly runs at 20% modulation, but for a longer period of time, (which I think is what the goal of a condensing boiler is).  Most importantly is that the return temperature is under 140* now, and more condensate is being produced than before.  (Don't know if longer run times will make the electric bills any higher, but then again it's fan speed is much lower as well).

I could absolutely say that the heat coming from the copper fin Embassy Panel Tracks is more of a gentle, even, and constant heat now.   (On the Embassy website the BTU chart only goes down to 170*, but on Slant Fin it goes as low as 110* and both seem to be very similar in design).  My downstairs zone is programmed to set back to 64* overnight and come up to 68* by morning (I ran it at 70* for the most part yesterday) and my upstairs zone sets back to 63* overnight while we sleep, and comes up to 67* in the morning.  All was fine and very comfortable.  The thermostats are set so that when I program a temperature in for a particular time, it compensates for the rise in temperature and it is at that set temperature by the time I programmed.  I will have to see during the week if it's coming to my programmed temperature as quick as it used to when the setpoints were 40* higher, or if I have to set the time a little earlier to compensate for a slower rise in temp.   

So far, so good, and thank you for the Ashrae links, there was some good information and makes me feel more comfortable in running the lower temperatures through the baseboards.

Vinny.

Zman

Outdoor reset

Vinny,

that sounds pretty good. On your boiler the setpoint B(1)is not the same as the top of your curve (F3).

The only setting I would absolutely change is  B4 (B9). to at least 100.

The warm weather end of you curve will not perform at all in the 70's with hot water baseboard.

Carl

Vinny_5

Carl

Maybe I am missing something and don't get what you are saying.

 B4 is the offset which has a maximum setting of 20* which is what I have it set at, and B9 is the setpoint for SH3 which I don't use.

SH1 is for 1st floor, SH 2 is for 2nd floor.  SH 3 is unused in my application.

Also there is a typo in the manual regarding F3-setpoint at low outdoor temperature.  I believe I have that set at 160* which is the 140* setpoint plus 20* offset.  It also mentions that if the user setpoint is lower (in my case 140*) then it will be limited by the user setpoint instead. I think it can't hurt keeping it at 160* since that is the max combined total of setpoint plus offset.  The manual says the ranges are -40* to 104* which is incorrect.  Hope what I am saying makes sense and please correct me if you see something wrong.

Otherwise, it is working out well with the low temperatures for now and most importantly no lockouts...LOL

Vinny.

Zman

Outdoor reset

Vinny,

Look at the graph on page 22.

The ends of the graph are determined by F1,F2,F3,F4 for curve SH-1 and F1,F2,F8,F9 for SH-2. The computer in your controller calculates the correct boiler temp based on the actual outdoor temperature. As an example based the numbers I suggest(and your low temp day of 10') below the computer would calculate about 130 degrees on a 32 degree day.







By changing the setpoint (B1 and B2)you are just squashing the upper end of the curve, you are not changing the curve.(see the dashed line on the graph)







If it were mine I would start with this:







F1 = lowest outdoor temperature seen in a typical year



F2= 65'



F3 and F8 = 160'



F4 and F9 = 100'



B1 and B2 =160'



I would leave the differential and the offset at default.



Once you set it up, If you find you are not getting the desired results

at higher outdoor temps adjust F4 and F9. If your trouble is at lower

outdoor temps adjust F3 and F8. The beauty of you system is you can

adjust on a zone by zone basis, ie adjust F3 but not F8



Hope this helps,

Carl

Vinny_5

Carl

Thanks for the advice. It is appreciated.   I don't think I will get to see the difference any more this heating season, but I will set  it up now so that I don't have to mess too much with it next season. 

Vinny.

Vinny_5

Hello, can use some advice again

Thanks for all the past input and advice regarding the issues I was having in with the Knight in the past.  It has worked flawlessly since adjusting the outdoor reset numbers and such.  A few recommended having the Knight control the DHW demand, so I waited for the heating season to end to order a 10K sensor kit. 

I apologize for adding to my almost 3 month old thread, but today I received and installed the 10K sensor for my Boilermate so my Knight can take over the hot water production, as opposed to the thermostat on the Boilermate.  Install took less than 5 minutes, and now the Knight displays the actual tank temperature and modulates accordingly. 

What I was hoping for is some input from the Lochinvar guys on the forum as far as settings are concerned.  Default tank set point is 125*, set point differential is 6*, offset is 10*,  differential is 20*, minimum setpoint is 60*, maximum setpoint is 140*.  So far the only thing I changed is the tank set point, which I lowered to 115*, as 125* is a little hot for my liking. Otherwise, everything else is at factory defaults.  Is there anything that you can suggest as far as tweaking the other numbers mentioned?

Thanks in advance, Vinny.