Advice needed on Tarm plan

[free75degrees]

I could use some help from all of the hydronic gurus out there, so if anybody has time to critique my piping plan, I would greatly appreciate it.

I am a novice so I want to keep things as simple as possible with my Tarm solo 40 install. In the diagram below, everything from the oil boiler to the right is the current setup (except for the zone valve just above the oil boiler). The current setup has been in place for a couple years and works fine. My plan is to add everything else to the left. There are basically 4 states for the system which are described in the table on the diagram.

Does anybody see any problems with this plan? Any suggestions?

 

[MrEd]

what controls the opening and closing of all those ZV's? to make sure they work in the right sequence together?

 

[free75degrees]

I have an arm based single board computer similar to the one that nofo uses. I'll use that with some relays to control the zone valves and circs. I'll also have some ds18s20 temp sensors in the tank, on the boiler in and out lines, and as thermostat replacements to help the system figure out which state to be in.

 

[kabbott]

The one thing I see that may cause a problem is when heating house with tank the coils and a zone valve will be on the suction
side of the 010 and expansion tank on the outlet.
I dont see a simple way to change that without changing your existing plumbing. With that said my own system was plumbed with the circulators
on the return pumping into the expansion tank, and I have seen dozens of systems work fine that way,but that much head loss between the ex tank
and suction side may cause problems.

Cant wait to see how your control system works out, I would love to do something like that but i dont no much about programming(in the last 20 years anyway lol)
I know my way around linux and pc's pretty well but after looking over nofossil's source I was lost.

 

[jebatty]

Do you think your Extrol 30 with a 2.5 gal acceptance is sufficient for this system? The Tarm itself has about 55 gal, plus plumbing. You might consider adding another exp tank on the suction side of 010. Also, depending on your elevations, you might need an air scrubber/vent on the Tarm side high point. The Tarm has 1-1/4 fittings, nothing wrong with using 1-1/2 on the supply/return sides though.

 

[Nofossil]

Looks good to me, with the suggestions already mentioned above. My only other concern is that the zone valves that are in oil and wood primary loop need to be larger orifice than the standard zone valve. Normal zone valves are designed to create a significant flow restriction so that there will be approximately equal flow in each zone when more than one zone is open at a time. Might be way more flow restriction than you want in your primary loop.

ds18s20

 

[free75degrees]

Do you think your Extrol 30 with a 2.5 gal acceptance is sufficient for this system? The Tarm itself has about 55 gal, plus plumbing. You might consider adding another exp tank on the suction side of 010. Also, depending on your elevations, you might need an air scrubber/vent on the Tarm side high point. The Tarm has 1-1/4 fittings, nothing wrong with using 1-1/2 on the supply/return sides though.

Yes, I do need to add some expansion on the Tarm side. I'll add that, thx. The elevation is about the same as the oil side. Should I still add another air scrubber/vent?

I was thinking of using 1 1/2" black pipe because is does not cost much more. Maybe 1 1/4" makes more sense though to reduce cost of fittings, etc.

Thanks a lot for the advice.

Marc

 

[free75degrees]

The one thing I see that may cause a problem is when heating house with tank the coils and a zone valve will be on the suction
side of the 010 and expansion tank on the outlet.
I dont see a simple way to change that without changing your existing plumbing. With that said my own system was plumbed with the circulators
on the return pumping into the expansion tank, and I have seen dozens of systems work fine that way,but that much head loss between the ex tank
and suction side may cause problems.

Cant wait to see how your control system works out, I would love to do something like that but i dont no much about programming(in the last 20 years anyway lol)
I know my way around linux and pc's pretty well but after looking over nofossil's source I was lost.

Thanks. This is exactly why this site rocks - I would have never known that that could be a problem. What would be the symptom of having the circ between the coils and expansion? Does adding another expansion the the left of the circ010 help?

Maybe I could move that entire 4 ZV/Circ configuration to the return side of the Tarm loop. Would that fix this problem?

 

[free75degrees]

Looks good to me, with the suggestions already mentioned above. My only other concern is that the zone valves that are in oil and wood primary loop need to be larger orifice than the standard zone valve. Normal zone valves are designed to create a significant flow restriction so that there will be approximately equal flow in each zone when more than one zone is open at a time. Might be way more flow restriction than you want in your primary loop.

ds18s20

Good point about the head. I should research that a bit more. I was looking at taco 573, which has 1 1/4 inlet/outlet, but I didn't find much info on head loss for that circ. Maybe I should consider an EBV. Taco makes an EBV which only goes up to 1". Do you think reducing to 1" and using the taco EBVs would be better than 573s?

 

[jebatty]

The elevation is about the same as the oil side. Should I still add another air scrubber/vent?

I think this really depends on getting the air out of the system the first time. You just want to be sure to eliminate any air-lock points. A vent without a scrubber might also be just fine at a high point on the Tarm side.

 

[in hot water]

My concern with this piping is the potential to have the 00100 and 007 in series when a zone calls? Without know exactly what is in those zones, it would be hard to model.

Lets assume zone 1 is calling, both the circs are running. Assume zone 1 is 20 feet of 3/4" baseboard. What is the flow rate and velocity through that loop?

The expansion tank connection or PONPC is another concern. Looks like the 0010 is pumping towards that point? I'm not sure how in a parallel piping both ircs could "pump away" from the PONPC.

Will it work/ No doubt. Is it ideal????

If you don't mind I'll send this drawing to the engineers at Taco for an opinion.

 

[kabbott]

My concern with this piping is the potential to have the 00100 and 007 in series when a zone calls? Without know exactly what is in those zones, it would be hard to model.

I agree, when say DHW calls for heat 010 will pump more volume then a single 007 and may create flow in other zones.
I would think the 010 only needs to run when charging tank.??

What if you put 010 in series with zv-c and eliminate zv-b and zv-d, open zv-a zv-c or zv-e and let 007 draw through which ever source is open?
only run 010 to charge tank.

 

[free75degrees]

Lets assume zone 1 is calling, both the circs are running. Assume zone 1 is 20 feet of 3/4" baseboard. What is the flow rate and velocity through that loop?

Is it possible for the flow rate/velocity to be too high? If so, why, what would happen? I wanted to use a 010 for charging discharging from the coils since they have a large head drop. If the 010 in series with the 007 zone circs is a bad idea, then maybe I can pipe it to use the 010 just for the coils and a separate 007 for the Tarm circ.

The expansion tank connection or PONPC is another concern. Looks like the 0010 is pumping towards that point? I'm not sure how in a parallel piping both ircs could "pump away" from the PONPC.

If I were to move the 010 circ to the Tarm return side then it would at least not be as close to the PONPC. It would be closer to halfway around the circuit. Would this be better?

If you don't mind I'll send this drawing to the engineers at Taco for an opinion.

No, I do not mind, in fact that would be hugely appreciated. Should I redraw the diagram with some of the suggestions first?


Thanks a lot for the help. Sorry if I sound like a complete amateur (I am, but I am willing to learn).

Marc

 

[free75degrees]

What if you put 010 in series with zv-c and eliminate zv-b and zv-d, open zv-a zv-c or zv-e and let 007 draw through which ever source is open?
only run 010 to charge tank.

hmm, right now the 007s work fine drawing from the oil boiler. Do you think they would be fine to draw through the extra 60 feet of black pipe and the Tarm as well? My largest baseboard zone is about 60 feet of 3/4" baseboard and about another 50 feet of 3/4" pex supplying them (all in series).

Thanks for the help,
Marc

 

[pybyr]

[Is it possible for the flow rate/velocity to be too high? If so, why, what would happen?
....
Sorry if I sound like a complete amateur (I am, but I am willing to learn).

Marc

on your first point above, from what I have been able to glean so far from the various stuff I've tried to read and digest, you always want the water velocity to be _above_ 2 feet per second, because at lower speeds, air gets trapped and stays in little nooks and crannies, which leads to potential corrosion problems. For residential purposes, it's apparently also strongly recommended to keep velocities _no higher than_ 4 feet per second, because above that, you may have noise from the fast-moving flow. If you get way above that, say above 8-12 feet per second, the water velocities can supposedly actually internally erode and gradually eat through portions of the piping, resulting in eventual leak/ failure.

I get the impression that if you won't be phased by potential noise, such as with buried lines, or things far away from living space, there's some "gray area" above 4 feet per second (bot not too far above) that won't cause any physical problems

on your second point, lots of us on here are amateurs, although thankfully there are some pros who are generous with their knowledge to keep us on course. And even amateurs can come up with good new ideas. The mix seems to be good at generating and fostering interest and innovation, which makes this place great.

 

[kabbott]

I would think they will be fine through the tarm but I am not sure about drawing through the coils in the tank plus the zone valve.
Lets see what the pro's think.

 

[Nofossil]

Good point about the head. I should research that a bit more. I was looking at taco 573, which has 1 1/4 inlet/outlet, but I didn't find much info on head loss for that circ. Maybe I should consider an EBV. Taco makes an EBV which only goes up to 1". Do you think reducing to 1" and using the taco EBVs would be better than 573s?

If I can correctly read Taco's data sheet, the 573 has a cv of 7.2, equivalent to 130 feet of 1 1/4" plumbing.The EBV is lower flow restriction. Interestingly, the 3/4 EBV looks to be lower than the 1". Could be a typo.

 

[SteveJ]

Very cool to see yet another custom embedded arm controller... I think nofossil has started a revolution!!

Plumbing questions
1. Does the Tarm have a built in circulator? If not, I think you need a pump between the termovar and the Tarm to get flow.
2. Why did you chose to have the zone valves and circs in the supply line instead of the return line? The old argument is that everything lasts longer in the cool side...
3. I assume all the zv are normally closed. Is the automag loop heat load large enough to handle a full load from the Tarm if the controller goes out?

Geek stuff (about the controls)
1. I would like to see your controller code if you don't mind - curious about the timing and polling, etc.
2. Are you using the TS-7260, TS-9700, DIO-64 similar to nofossil?
3. How many power supplies and relays are you up to?
4. What voltages are you running?
5. What is your fail-safe mode if the arm goes down?

Great stuff - do you have logging and will you post charts like nofossil?

 

[jebatty]

Does the Tarm have a built in circulator? If not, I think you need a pump between the termovar and the Tarm to get flow.

A pump is not needed here, but a control is needed to turn on circulation when the Tarm is at or above a determined temp.

My system is very simple compared to what's proposed. I have an aquastat on the return side of the Termovar. It is set at 150. When the Tarm is fired, hot water by thermo siphon moves from supply through the Termovar to return. At 150 the aquastat switches the circ on. The Termovar maintains return temp above the aqusatat off point (130-140), and the circ continues to run until the wood load is burned and/or return temp drops below the off point.

 

[DaveBP]

"If I can correctly read Taco’s data sheet, the 573 has a cv of 7.2, equivalent to 130 feet of 1 1/4” plumbing.The EBV is lower flow restriction. Interestingly, the 3/4 EBV looks to be lower than the 1”. Could be a typo."

I was puzzling over the same apparent paradox recently so I had to go back to Siegenthaler's text book (which I am reading sloooowly) and 'relearned' that Cv is the number of GPM's that will create a one pound pressure difference across it. So a higher number is less friction across the valve. The equivalent length of pipe paradox I could only resolve by assuming that they mean the equivalent length of pipe the same size as the valve fitting. So that a 3/4" valve rating is so many feet of 3/4" pipe and the 1- 1/4" valve rating is so many feet of 1-1/4" pipe. 1-1/4" pipe has one tenth the friction per foot that 3/4" pipe does so the longer equivalent length can be less friction.

 

[Nofossil]

"If I can correctly read Taco’s data sheet, the 573 has a cv of 7.2, equivalent to 130 feet of 1 1/4” plumbing.The EBV is lower flow restriction. Interestingly, the 3/4 EBV looks to be lower than the 1”. Could be a typo."

I was puzzling over the same apparent paradox recently so I had to go back to Siegenthaler's text book (which I am reading sloooowly) and 'relearned' that Cv is the number of GPM's that will create a one pound pressure difference across it. So a higher number is less friction across the valve. The equivalent length of pipe paradox I could only resolve by assuming that they mean the equivalent length of pipe the same size as the valve fitting. So that a 3/4" valve rating is so many feet of 3/4" pipe and the 1- 1/4" valve rating is so many feet of 1-1/4" pipe. 1-1/4" pipe has one tenth the friction per foot that 3/4" pipe does so the longer equivalent length can be less friction.

If you look at their data sheet, the 3/4" EBV has a higher cv than the 1". In any event, bothe are higher than the traditional 1 1/4" zone valve. I have an 3/4" EBV, and it's definitely a larger orifice than the traditional Honeywell zone valve.

 

[DaveBP]

"If you look at their data sheet, the 3/4” EBV has a higher cv than the 1”. In any event, bothe are higher than the traditional 1 1/4” zone valve. I have an 3/4” EBV, and it’s definitely a larger orifice than the traditional Honeywell zone valve"


Now that I found the EBV valve data I see what you mean. I was misunderstanding the data for different valves. So why does the larger EBV have a lower Cv?

 

[Nofossil]

"If you look at their data sheet, the 3/4” EBV has a higher cv than the 1”. In any event, bothe are higher than the traditional 1 1/4” zone valve. I have an 3/4” EBV, and it’s definitely a larger orifice than the traditional Honeywell zone valve"


Now that I found the EBV valve data I see what you mean. I was misunderstanding the data for different valves. So why does the larger EBV have a lower Cv?

Like I said, I think it might be a typo. If you're interested in these valves, I'd call them. They have real engineers who will actually talk to you.

 

[free75degrees]

Thanks you guys soooo much for all of the advice. I think understand what everybody is saying and have incorporated the various pieces of advice in to the new plan below. Please let me know if this fails to address any of the problems brought up previously.

Zone Valves A, B, and C are all Taco EBVs. I love the fact that I can get these EBVs in normally closed OR normally open. Here is what I am thinking:
ZV-A is normally open.
ZV-B and C are normally closed.

The cool part is that all 3 ZVs can be controlled by ONE signal. That's right, just one signal for all 3 ZVs can get me my 4 states (other signals needed for circs).
- No signal sent to ZVs: A is open and B and C are closed. This works for Tarm heating house and tank heating house.
- Signal sent to all ZVs: A is closed and B and C are open. This works for Tarm heating tank and oil heating house.

I am thinking a 007 IFC will work for discharging the tank because there will also be the zone valve(s) in series helping out. For the circ feeding the Tarm, I think I will something stronger like an 010 because that will be the only think charging the tank.

Any thought or issues people can see with this setup?

Thanks,
Marc

 

[free75degrees]

Very cool to see yet another custom embedded arm controller... I think nofossil has started a revolution!!

Plumbing questions
1. Does the Tarm have a built in circulator? If not, I think you need a pump between the termovar and the Tarm to get flow.
2. Why did you chose to have the zone valves and circs in the supply line instead of the return line? The old argument is that everything lasts longer in the cool side...
3. I assume all the zv are normally closed. Is the automag loop heat load large enough to handle a full load from the Tarm if the controller goes out?

Geek stuff (about the controls)
1. I would like to see your controller code if you don't mind - curious about the timing and polling, etc.
2. Are you using the TS-7260, TS-9700, DIO-64 similar to nofossil?
3. How many power supplies and relays are you up to?
4. What voltages are you running?
5. What is your fail-safe mode if the arm goes down?

Great stuff - do you have logging and will you post charts like nofossil?

Thanks for the inputs, I think my new design handles your 1st 2 points. For the 3rd, I still need to research the sizing on the overheat loop.

Geek stuff:
1 - I would be happy to share my code, but at this point I have only written a utility in C to read the digital temp sensors. I did that a while ago because that was the only part I was unsure of and I wanted to make sure it would be do-able. The timings are a little tricky and I used a system call to turn off the kernel's task scheduling while the program is running so that some other task would not get some cpu time and screw up the timings. The utility is currently on a hard drive inside my old computer which is not hooked up.. I'll post it when I get the HD out and connected to my new comupter. For the rest of my code I am probably going to use C to write a utility that will send signals to the relays, then write the rest of the code to manage the whole system in Perl. I am going to finish up the plumbing then move onto the controls, so I'll probably be finishing just in time for heating season.
2 - I am using a ts7800 and i am using it's own DIOs. My plan is to use the ts7800 to control some small relays which will then control the relays on a taco relay board.
3 - I haven't totally thought this through yet because I have been focused on my tank, chimney, and plumbing so far but I think I am going to use my existing 6 zone taco relay board and PS for my zones, then maybe another similar board for the rest of the stuff. Depending on the plumbing design I decide on, I think I may only need a few more relays. Then, for each 24V relay I will use corresponding smaller relays inside the ts7800 case.
4 - Which voltages are you asking about here?
5 - Well, not totally ironed out yet, but with the current design, the normal state is that either the Tarm or tank can heart the house. Then, inside my Arm board, I am going to wire small manual 3 pole switches in series with the 3 pole relays, so that I can always manually override whatever state each relay is in.

Yes I will definitely have logging, which is one of the main reasons I liked the idea of using something with more power than necessary, like the arm. Eventually I would like to do cool stuff like be able to turn on my future snow melt zone from the web while at work, use the arm to also control my future irrigation system and pull weather forecast data from the noaa web service so that I can keep the water turned off when rain is in the forecast, etc, etc.

Marc