Fiddling with Return Temperature

[JohnDolz]

What about the zone circs on speed 1 and the supply circ on speed 2?

They're supposed to ramp up & down to meet demand - so was thinking the supply would do that, as more zones opened. But then that would change the pressure diff on the zone circs - there would maybe be some yo-yoing going on there to some extent? Interesting...

Good thought, I might try that on pressure setting #2 rather than speed (watts setting). I just noticed this yesterday and haven't played with all of the options yet. I am still hoping to connect with Grundfos to get their perspective. My installer is trying to get me to order zone valves but I think that is because he likes my coffee (roast my own but that is a whole other forum)! I thought the Auto mode would have done what you are suggesting but doesn't seem to be the case or at least I am not understanding it. If I had to bet I would say that there is a ton of this going on out there and most folks are pushing through their bypass without knowing (or never given it any thought). It just so happens that I tinkered with the bypass and one of my points of least resistance was my DHW loop which happens to have a temperature sensor that pops up on one of my displays. When I had my Taco pumps in and an open bypass none of this even occurred to me. Ignorance is bliss but in this case my wife is younger than me so no point in leaving her next dude any cash!

 

[maple1]

My one Alpha runs 5 zones (zone valves) on constant pressure 1.

I would try your zone circs on constant speed 1, and your other one on constant pressure 1. Then if that's not enough flow when all zones open, up the second one to 2.

Not sure what you've tried so far or where you're at - I guess when I'm talking Alpha settings, I'm always talking/thinking constant pressure settings, and not constant speed. So that's also what I'm reading.

 

[JohnDolz]

I was talking constant speed because this allowed me to get flow rate to the lowest possible and to the lowest wattage usage (they were down to about 5 or 6 watts each). When I was on constant pressure I was getting much higher energy use. I switched over to what you suggested and from the demand side, looks like pressure setting # 1 is = to speed setting #2 (same GPM & Watts). For the main circ pressure setting # 2 is basically equal to the output of the Auto setting. Pressure setting #1 is a little lower. I'll leave things there for a bit and see what happens. Not even sure what I am judging at this point but appreciate the thoughts and suggestions.

 

[maple1]

I tried to get my head around that fancy looking pump curve chart in the manual - but couldn't....

 

[JohnDolz]

I tried to get my head around that fancy looking pump curve chart in the manual - but couldn't....

That's OK, I couldn't get my head around the simple diagram that Bob included. My Design temp is controlled by a curve which is dictated by the Outdoor Reset (plus my Indoor sensor but let's ignore that for now so your head doesn't hurt). We start with the graph on top, it basically shows 3 different possible slope curves (you can create any slpe you want as you can choose the design on a degree by degree basis). You pick the design temp that you want at -15C and then the curve "builds" itself from there. On the right design will be 20c when outdoor temp is 20c, you are picking the design at -15c and then you can see where it basically lands on the left hand side. You can then shift the slope up or down via the "Adjustment" shown in the 2nd graph (basically allows you to extend the end points - for me I have a kick heater in an addition that I use as my office so I need to adjust my slope so that I run hotter design when it is not quite so cold out otherwise even the low temperature aquastat will not kick in - office addition is an HVAC nightmare, I put in a Mitsubishi mini-split that works to 0 degrees F so life is now good).

Here are the instructions under the graph (by the way my Indoor Sensor overrides the Slope when it is not hitting my desired target temperature, critical item when I recover from nightly setback):

If it is cold outdoors (cold winter) and the room temperature is too low. Increase the
slope with 1-2˚C.
If it is cold outdoors (cold winter) and the room temperature is too high. Decrease
the slope with 1-2˚C.
If it is warm outdoors (average autumn/spring) and the indoor temperature is too
low. Increase the adjustment with 1-2˚C.
If it is warm outdoors (average autumn/spring) and the indoor temperature is too high.
Decrease the adjustment with 1-2˚C.
Wait at least 24 hours between adjustments and changes due to slow response of
heating.

 

[JohnDolz]

My one Alpha runs 5 zones (zone valves) on constant pressure 1.

I would try your zone circs on constant speed 1, and your other one on constant pressure 1. Then if that's not enough flow when all zones open, up the second one to 2.

Not sure what you've tried so far or where you're at - I guess when I'm talking Alpha settings, I'm always talking/thinking constant pressure settings, and not constant speed. So that's also what I'm reading.

Can I pick your brain for a second? What does your alpha show for GPM when it is running? Does it stay fairly consistent regardless of how many zones start calling? Thinking that this is the direction that I may ultimately end up going (1 pump 5 zone valves) because right now my DHW loop as the weak link that ends up absorbing the "extra" flow (creates a nightmare for heating my DHW). My temporary fix may be just 1 more zone valve to isolate the DHW but that "extra" water is going to go somewhere. I thought I had it dialed in but when I increased the zone demand the higher flow rate pushed my house temp up and circs that normally run 24x7 turned off and the water again found the DHW loop. Basically I will drive myself insane trying to get everything in sync and then when outdoor temp shifts so does everything else. The obvious answer is open the bypass (which is what I am doing for now), accept that some BTU's are being wasted as they flow back to the bottom of storage via the Return and go have a glass of wine but what challenge would that be!

 

[maple1]

The GPM read out varies with how many zones are open. Not sure of the range, I will try to remember to observe it more next time I am down there & all the zones are open - but minimum it shows is 1gpm, when just my DHW loop is calling.

What is the 'nightmare' - do you mean your DHW gets too hot? Did you try throttling down your DHW loop some by partly closing a ball valve on it? (Does it have its own Alpha?). Then again, throttling won't be the thing to do if that one Alpha is on a constant speed setting.

I'm still kinda thinking you should be able to find a balance point - these Alphas have a lot of different settings/operating modes and are very flexible. Did you try constant pressure 1 on your main pump? But I guess though, with what I think your setup is, that your one main pump would just keep pumping if it is on a constant pressure setting even if no zones were calling, since there is nothing to block the flow through them in the absence of zone valves - but (another 'then again') with your constant flow scenario, maybe you don't have or want a time when no zones are calling?

Some circle talk...

 

[JohnDolz]

The GPM read out varies with how many zones are open. Not sure of the range, I will try to remember to observe it more next time I am down there & all the zones are open - but minimum it shows is 1gpm, when just my DHW loop is calling.

What is the 'nightmare' - do you mean your DHW gets too hot? Did you try throttling down your DHW loop some by partly closing a ball valve on it? (Does it have its own Alpha?). Then again, throttling won't be the thing to do if that one Alpha is on a constant speed setting.

I'm still kinda thinking you should be able to find a balance point - these Alphas have a lot of different settings/operating modes and are very flexible. Did you try constant pressure 1 on your main pump? But I guess though, with what I think your setup is, that your one main pump would just keep pumping if it is on a constant pressure setting even if no zones were calling, since there is nothing to block the flow through them in the absence of zone valves - but (another 'then again') with your constant flow scenario, maybe you don't have or want a time when no zones are calling?

Some circle talk...

Thanks, took a quick look to see if there was a way to Private message so I could stop wasting everyone's time, if you like my email is [email protected]. When I set my "main" Alpha to constant Pressure 1 it is pretty much pushing 6 or 7 GPM (if I put it on speed 1 I can get it down to 1 GPM). If all of my zones shut off the main alpha shuts off as will so I am OK. It is when I drop to just 1 zone calling that I start having water pushed elsewhere. Ideally I want 3 zones running 24x7 (we can debate the cost of btu's vs, the cost of running the pump) but with these huge temperature swings outside I can't always control things. The types of nightmares I am talking about are: 1. I usually run extremely low design temps so basically I am running cold water into my DHW tank (i.e. I bet if I go look design is under 100F today) 2. this flow ends up dropping the temp of my DHW tank which is tied to 2 sensors, when temp drops I have a separate loop from my thermal storage that will heat my DHW, this will start to push 147 degree water into the DHW tank but it will hit the "extra" house design temp water that is pushing through a circ that is turned off (this pump is at the tail of my Supply manifold and kicks on when I need my propane boiler to heat DHW - I guess if I wanted to do major restructuring I could think about pulling it out and creating a new loop for propane DHW) this will result in a blended supply going into DHW that will be way too low (unless it is very cold outside). Eventually the DHW temp will drop enough that my propane boiler will kick in, get the DHW tank up to the propane boiler target temp, shut off and the cycle will start over again. 3. If it is very cold out (single digits or below) I will end up with much hotter water than I want, the family won't expect it and then we are off to the Emergency Room. I have already pulled Tom Caldwell down this rabbit hole with me so feel free to walk away now shaking your head, I would completely understand. Happy to take the conversation offline, if you like - just email me.

 

[velvetfoot]

If you go the zone valve route, I replaced the flo check valves that were originally on the zones (2) with the zone valves. Had to cut them out, but what I'm saying is there's room there. My problem, I guess, is that the boiler feed pump added too much ooomph. Dialing it down helped, but I did the valves anyway. Another thing, if you did put in zone valves, why bother reconfiguring the system for one constant pressure pump-just leave the circs in for at least redundancy and no piping work?

 

[velvetfoot]

No problem with me keeping it public...it's interesting.

 

[maple1]

One more for here for now - curiosity & all that, I just opened all my zones & checked. 7 gpm/25 watts. I am also burning right now, the Alpha may be getting a boost from the loading unit pump - not sure on that part.

 

[maple1]

I think your system configuration is getting to be a bit over my head - so I think I will try to avoid the rabbit hole on that.

Won't likely walk away shaking my head, it is interesting - but beats me.

EDIT: One more quickie from the edge of the hole - prioritize DHW by plumbing it on it's own separate supply loop from top of storage? Return to middle? Seems to be two quite different supply temp requirements there. (Now taking one step back...)

 

[velvetfoot]

I had a couple of extraneous thoughts.

-You're mixing the entire system down and that's the main source of heat. So, you don't have higher temp source for, say, the kick heater. Even though there's a separate zone for the dhw tank, the low temp gets involved there too. Low temp distribution is working out except for those two instances, and the excellent mini split is taking care of the off. There probably isn't a separate zone for the kick heater anyway, and it'd be a big deal routing pipe with a pump out there just to get a higher temp mix.

-With the DHW, however, since all the stuff is in the boiler room, can you isolate that from the main mixing valve so that it gets higher temp water from the main storage tank? Also, I'd put in an anti scald (mixing) valve around the dhw tank just in case, plus you can charge that up as high as you want with no worries.

-Now, how about this: my original oil boiler system never had any boiler circ pump-I think that's generally the case. It sounds like you have an additional feed pump from the main storage tank in front of the zone pumps? Is that really necessary? Everything is pretty close.

 

[JohnDolz]

If you go the zone valve route, I replaced the flo check valves that were originally on the zones (2) with the zone valves. Had to cut them out, but what I'm saying is there's room there. My problem, I guess, is that the boiler feed pump added too much ooomph. Dialing it down helped, but I did the valves anyway. Another thing, if you did put in zone valves, why bother reconfiguring the system for one constant pressure pump-just leave the circs in for at least redundancy and no piping work?

Thanks I would think piping work is needed anyway to get the zone valve in and then as Mr. Rohr has suggested I will most likely need to add balancing valves. Each "zone stack" wold then have a alpha, a zone valve and most likely a balancing valve (haven't educated myself on those yet). If I remove the alphas I have 5 backups (less whatever maple1 purchases from me). My installer is a lot smarter than me so I am just gathering some info for him. Thinking the yanking of the alphas, should it happen is a summertime project. At some point I may just buy a Corvette instead.

 

[JohnDolz]

No problem with me keeping it public...it's interesting.

Thanks, just want to be sensitive to others, this should not be the johndolz forum but hopefully it is fun reading for folks and we all learn something.

 

[velvetfoot]

Why would you need a balancing valve? Even my Ecocircs are speed adjustable. Your Alphas are too, right?

 

[velvetfoot]

Thanks, just want to be sensitive to others, this should not be the johndolz forum but hopefully it is fun reading for folks and we all learn something.

Hey, I started the thread!

 

[JohnDolz]

I think your system configuration is getting to be a bit over my head - so I think I will try to avoid the rabbit hole on that.

Won't likely walk away shaking my head, it is interesting - but beats me.

EDIT: One more quickie from the edge of the hole - prioritize DHW by plumbing it on it's own separate supply loop from top of storage? Return to middle? Seems to be two quite different supply temp requirements there. (Now taking one step back...)

Thanks and understand, let me know what you see on the alpha for GPM when various # of zones open/close. Regarding pulling from to vs. middle, that flips me back to the thread on thermal storage options and why if I had to do it over again I might go with an Effecta Accumulator tank, they are built for all that stuff. In my world I use mixing valves driven by actuators controlled by my wood boiler. Since wood heated DHW is on its own loop I have a design temp that is separate from my house design temp. Basically I mix water from the top of the tank with Return water to hit the design temp that is controlled by the Effecta boiler (Outdoor Reset/Indoor Sensor & Cylinder Temp for DHW). As an FYI I am a sales guy that has zero mechanical skills and started this with zero knowledge, I have slowly gotten sucked into the hole and keep thinking that I have to be close to the bottom. Step away from the hole and be safe.

 

[JohnDolz]

Why would you need a balancing valve? Even my Ecocircs are speed adjustable. Your Alphas are too, right?

The balancing valves would come into play because if I installed Zone Valves I would deactivate (or remove the zone alphas).

 

[JohnDolz]

Hey, I started the thread!

Yes and I seem to have hijacked it.

 

[JohnDolz]

I had a couple of extraneous thoughts.

-You're mixing the entire system down and that's the main source of heat. So, you don't have higher temp source for, say, the kick heater. Even though there's a separate zone for the dhw tank, the low temp gets involved there too. Low temp distribution is working out except for those two instances, and the excellent mini split is taking care of the off. There probably isn't a separate zone for the kick heater anyway, and it'd be a big deal routing pipe with a pump out there just to get a higher temp mix.

-With the DHW, however, since all the stuff is in the boiler room, can you isolate that from the main mixing valve so that it gets higher temp water from the main storage tank? Also, I'd put in an anti scald (mixing) valve around the dhw tank just in case, plus you can charge that up as high as you want with no worries.

-Now, how about this: my original oil boiler system never had any boiler circ pump-I think that's generally the case. It sounds like you have an additional feed pump from the main storage tank in front of the zone pumps? Is that really necessary? Everything is pretty close.

Let me gives these a try:

Kick Heater - I changed it to a low temp aquastat but often design temp is still too low. Doesn't matter much because the thing is way underpowered for the job it is asked to do. I looked at the cost to add a low temp emitter (crazy 's) but I would still have a cooling issue in the summer. Just a bad design all around. The minisplit resolved summer and winter issues. I drop that room to 55 at night, use the minisplit to do rapid recovery and then it just supports the kickheater. I work form a home office when not traveling and got tired of being cold or hot.

DHW - yes it is isolated when it gets heated with wood (see my other comment to malpe1). It is not isolate when heated by propane.

Feed pump before the zones - yes I need that one because it pulls through a mixing valve to give me the target temperature that I need.

 

[Bob Rohr]

Be aware that those GPM readouts on the small ECMs are just a calculation from the control.
There is no actual flow measuring device on them. We see errors of 60% or more on a regular basis.
Doing any calculations or balancing with that number would be a gamble.

 

[velvetfoot]

Feed pump before the zones - yes I need that one because it pulls through a mixing valve to give me the target temperature that I need.

Couldn't a zone circ do the job?

 

[JohnDolz]

Couldn't a zone circ do the job?

Don't know, maybe I will try disconnecting that pump and see what happens. Effecta designs systems with the pump in front of this mixing valve but then again they do not use zone valves.

 

[JohnDolz]

Be aware that those GPM readouts on the small ECMs are just a calculation from the control.
There is no actual flow measuring device on them. We see errors of 60% or more on a regular basis.
Doing any calculations or balancing with that number would be a gamble.

Understood and appreciated. I can see the #'s in my Indirect Hot Water Heater and can tie them back to flow temps (either high or low) so I definitely know I am getting "ghost" flow there. I can also feel the pipe going to the Modine Hydronic heater in my basement and can feel that it is getting flow (this is piped slightly;y larger than my zones). These 2 seem to be the weaker links are absorbing the excess pressure/water.