Mod CON? Or Power vent 85%?
Comments
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I was wondering about your situation this morning, 20F outside and windy!
Did you try diverting some of the CH water away from the downstairs zone with the ball valve?
If the majority of the CH water is flowing to the downstairs zone because the upstairs zone has higher head, raising the CH water temp isn't going to be terribly effective. You need to balance the zones so when both are running they get sufficient flow.0 -
^ I did. I actually shut 1 valve completely off on the lower level. As I stated earlier it has 2 feeds, one return. I also tried almost closing the main one. I am only running into this issue when both zones call for heat. Wonder If I should bump boiler to 100% output?
MAybe I should just install a globe valve on 1st zone. It cant hurt. Thing is, how do i test if both zones are balanced?0 -
If you're hitting setpiont (ODR calls for 140F supply and the boiler is supplying 140F SW) that means the boiler is keeping up.
If your not close to hitting target CH setpoint (ODR calls for 140F supply and the boiler is only supplying 130F SW)- increase boiler capacity.
You need to verify you have flow going to the upstairs zone.. when the upstairs zone valve opens is the pipe downstream of the ZV getting warm/hot? Is the return from that zone hot/warm or cold?
Even if you have insufficient radiation, the pipe supplying the first radiator in the upstairs zone should be warm on a call for heat.0 -
^ I am hitting setpoint. So i guess that rules out boiler capacity. I definitely have flow too. Rads are warm, and pipe return from upstairs is warm. So there is flow. I just dont think I have enough btu's at lower supply temps for the upstairs.
Edit, I am now at 63 upstairs, with thermostat set at 69.
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Guess it's time to bump up the ODR curve....
It's all theoretical till you hit your first cold windy day like today.
I must have adjusted my ODR curve twenty times my first winter with the mod-con.
If you need to use hotter water, use it.
Next summer see if you can add radiation upstairs.-1 -
^ I probably will. I could add at least 30 feet fairly easy. So just raise my supply water temp??0
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Right now it's 28F in our area.
What's your CH target for 28F?
Our DD temp here is 15F, why don't we consider a ODR curve based on that?
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Maybe time to go back and give the HTP default curve a try, but increase their outdoor low from 5F to 15F.
CH High 180F
CH Low 86F
Outdoor high 68F
Outdoor low 15F
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Min outdoor temp: 0NY_Rob said:Right now it's 28F in our area.
What's your CH target for 28F?
Our DD temp here is 15F, why don't we consider a ODR curve based on that?
Max CH water temp: 165
Max outdoor temp: 50
Min CH water temp: 120
I am back to this. I had this originally, but had some short cycling in november. I will give this a shot, see what happens the next few days. Boost is off BTW.0 -
Forgot to ask.... what's the GPM indicating on the Alpha with all zones open?
What mode & level are you using (Fixed speed I, II, II, CP I, CP II, CP III, etc..)?
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If the downstairs zone keeping up with its thermostat?Hydronics inspired homeowner with self-designed high efficiency low temperature baseboard system and professionally installed mod-con boiler with indirect DHW. My system design thread: http://forum.heatinghelp.com/discussion/154385
System Photo: https://us.v-cdn.net/5021738/uploads/FileUpload/79/451e1f19a1e5b345e0951fbe1ff6ca.jpg0 -
^ Everyone says the Alpha GPM reading is not accurate, easy test... bump it up to CP2.. see if that makes a difference on your upstairs zone.0
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So I inadvertently balanced my bedroom downstairs with the rest of the lower level, by closing the split zone a bit!! And going back to my original settings I just posted, I have also gained 2 degrees upstairs in the last 2 hours. I will leave it as is for another day or 2, and see what happens. Will keep you updated.NY_Rob said:^ Everyone says the Alpha GPM reading is not accurate, easy test... bump it up to CP2.. see if that makes a difference on your upstairs zone.
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Sounds good!
You might consider narrowing that setback to 2deg, it will shave an hour off the recovery time and you will get more flow to your upstairs zone.
I don't use any setback on our ground floor zone, it's got limited radiation and takes forever to rise 1deg with 115F supply water.0 -
Still struggling a bit today. Better but right now upstairs is 2 degrees below setpoint. If I change my min outdoor temp 5 or 10 degree higher, that should raise my supply temp at lower outdoor temps. Correct?0
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Did you have floor heat or baseboard?
My baseboard will take hours to hit the thermostat setpoint, but I am getting constant heat even though it says 67 it feels warmer0 -
I would lose the downstairs setback completely, I think that might cure your upstairs issue without sacrificing efficiency (moving out of condensing return temps by raising the curve temps).
If you still want downstairs setback, add upstairs radiation over the summer.
It was 13F here this morning, when I got up at 6:45am all three zones were running but at setpoint . I checked the CH water temp on the boiler display 133F. When I was using -2F setback on the downstairs zone earlier... it was never at setpoint even when I left for work at 8am and the upstairs zone was struggling to hit setpiont too. I believe that by keeping the downstairs zone at a set temp vs. setback, the warmer air is helping to warm the upper floors too.0 -
Yup, very cold this morning. Upstairs within 2 degrees of setpoint, down stairs cycled a few times. I am gonna try the no setback, but the wife will probably complain..lol.NY_Rob said:I would lose the downstairs setback completely, I think that might cure your upstairs issue without sacrificing efficiency (moving out of condensing return temps by raising the curve temps).
If you still want downstairs setback, add upstairs radiation over the summer.
It was 13F here this morning, when I got up at 6:45am all three zones were running but at setpoint . I checked the CH water temp on the boiler display 133F. When I was using -2F setback on the downstairs zone earlier... it was never at setpoint even when I left for work at 8am and the upstairs zone was struggling to hit setpiont too. I believe that by keeping the downstairs zone at a set temp vs. setback, the warmer air is helping to warm the upper floors too.
Maybe I should just open the upstairs zone?? Keep it on at all times??? Hmmmm? Open the zone valve, so when downstairs calls for heat, upstairs gets some, and when upstairs needs it's setpoint, it calls for it.0 -
^ Try that on a day you're home...Suzook said:Maybe I should just open the upstairs zone?? Keep it on at all times??? Hmmmm? Open the zone valve, so when downstairs calls for heat, upstairs gets some, and when upstairs needs it's setpoint, it calls for it.
I forgot and left the "apartment" zone open one evening, when I went in to check on mom the next morning at 7am... it was 76F in there!
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WOW! You almost cooked her! LOL. Now that its warmed up, both my zones are at setpoint. I will give the open zone a try, I just think there is too little fintube for the lower water temps. Warmer weather coming next week. Should mess me up again.NY_Rob said:
^ Try that on a day you're home...Suzook said:Maybe I should just open the upstairs zone?? Keep it on at all times??? Hmmmm? Open the zone valve, so when downstairs calls for heat, upstairs gets some, and when upstairs needs it's setpoint, it calls for it.
I forgot and left the "apartment" zone open one evening, when I went in to check on mom the next morning at 7am... it was 76F in there!0 -
^ Yeah, she thought 76F was real nice
I usually keep it 70F in there for her, our part of the house is 68F downstairs and 69F upstairs.0 -
^^HAHA. So upstairs zone open since noon. So far, so good. Temp is 68 up, 69 down. Lets see how things are tonight when its colder.0
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Well, keeping the upstairs zone open has worked out so far. Its maintaining temp, and downstairs is too. Lets see how things pan out on a really cold day.0
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> @Suzook said:
> ^ I am hitting setpoint. So i guess that rules out boiler capacity. I definitely have flow too. Rads are warm, and pipe return from upstairs is warm. So there is flow. I just dont think I have enough btu's at lower supply temps for the upstairs.
> Edit, I am now at 63 upstairs, with thermostat set at 69.
Just a side thought. But it’s possible with fin tube to reduce flow but increase supply temp and you might ride the heat transfer curve so that LWT off the zones goes down. Pumping too fast can hurt delta t. But you’ll get more capacity with the same supply temp.
Possible when things slow down it balances out a little. Resonance time increases that way.0 -
The faster the flow through any heat emitter the higher the AWT "average water temperature" in the emitter and the higher the output.
Here is a model from the IBR standard on fin tube baseboard. As flow slows heat output drops. Notice at 1 gpm it drops quickly as you start to lose the turbulent flow needed to transfer the heat energy from the water to the tube and fins.
Of course a limit to how fast you flow based on tube size and velocity. At around 5 feet per second velocity you will start to hear the water running through the tube, especially copper fin tube.
6 gpm in a 3/4 tube is doable, around 4 fps.
The goal is to be warm and comfortable in your home. Assuming you have enough emitter to cover the load at some SWT.
Running a higher SWT will lower the efficiency of the boiler a tad. With a mod con we strive for the lowest possible return, but staying warm may trump ultimate efficiency. Keep experiment with both flow rate and SWT to achieve the results you want.
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream
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Interesting read about flow through fin tube. I assumed the faster flow would lower the btu's thinking is was flowing too fast to extract the heat. But the opposite is true.. Very interesting.hot rod said:
The faster the flow through any heat emitter the higher the AWT "average water temperature" in the emitter and the higher the output.
Here is a model from the IBR standard on fin tube baseboard. As flow slows heat output drops. Notice at 1 gpm it drops quickly as you start to lose the turbulent flow needed to transfer the heat energy from the water to the tube and fins.
Of course a limit to how fast you flow based on tube size and velocity. At around 5 feet per second velocity you will start to hear the water running through the tube, especially copper fin tube.
6 gpm in a 3/4 tube is doable, around 4 fps.
The goal is to be warm and comfortable in your home. Assuming you have enough emitter to cover the load at some SWT.
Running a higher SWT will lower the efficiency of the boiler a tad. With a mod con we strive for the lowest possible return, but staying warm may trump ultimate efficiency. Keep experiment with both flow rate and SWT to achieve the results you want.0 -
Correct heat transfer is all-out temperature difference, delta T. The warmer the entire emitter the greater the best transfer to a colder space or object.
Of course we also consider pumping power (wattage) required when considering higher flow rates. Most residential systems, up to 120,000 or so low pressure drop boilers and fin tube should be able to be circulated with under 100W, maybe 1/2 that with ECM circulators.
Higher flow rates and lower deltas can cause boiler more cycling but with properly sized modulating burners, and all the newest control functions like ramp delay and electronic de-rate, that too minimized.
We are light years ahead of the single, fixed speed circulators, one speed often oversized boilers of the past.
It could take most of a heating season of trial and error to get your system dialed in to optimum comfort and performance, not many take the time to learn and fine tune systems, it really needs to be done by the occupants.Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream1 -
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream1 -
Too much flow will decrease DT though, so it's a balancing act to get it right. You don't want to underflow and fry your HX, but too much flow is not helpful either.
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I have my alpha on CP2....seems to be working well. Any idea how many watts cp2 is?? Now I am worried about my el use....geeez, i need to relax.NY_Rob said:Too much flow will decrease DT though, so it's a balancing act to get it right. You don't want to underflow and fry your HX, but too much flow is not helpful either.
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^ It will flash the wattage on the display.
It rotates from GPM to Watts constantly.0 -
^^ Yikes! Its official. I need to wear glasses all the time..I thought the upper word was wait...not watt. WOW!
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^ lol.... funny stuff right there
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My ocd setting in again. Look at my Alpha....Do I NEED to rotate the motor housing? Or is it more just for aesthetics??
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I would move the expansion tank and mount it to the wal or ceiling. Give it some type of support. If it gets water logged it could fall.
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njtommy said:
I would move the expansion tank and mount it to the wal or ceiling. Give it some type of support. If it gets water logged it could fall.
Sorry guys this is an old pic. Expansion tank is supported to the ceiling. Just curious about my alpha.Gordy said:
I remember bringing that up about 6 pages ago. Not good.njtommy said:I would move the expansion tank and mount it to the wal or ceiling. Give it some type of support. If it gets water logged it could fall.
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