[quote author="kabbott" date="1257034934"][quote author="Gooserider" date="1257033746"][quote author="huskers" date="1257030226"][quote author="Gooserider" date="1257026498"]
On the subject of plumbing for loops that flow in opposite directions, there was a thread a while back with a lot of debate about how best to do it. It seems the easiest / simplest / least expensive solution that developed was to just have one length of pipe with two pumps in it that face opposite directions, and wired so that only one pump could run at a time... According to Taco tech support, obviously as long as one doesn't use flow checks, the flow resistance of a non-running circ is essentially negligible, so you just run one circ to pump into the tank for charging, and the other to pump out of the tank for discharging... It avoided the relatively high cost of the multi-way valves (in most cases the pump was less), and was a simpler thing to plumb than any of the loops with check valve approaches.
Gooserider[/quote]
Thanks for the tip, I will search for that link. I was so focused on the pumps with the inline check valves, my mind didn't consider that option. So when boiler is hot the tank will be charging, when the boiler circ is off (ie. boiler less than 140*) and the temp at top of storage is adequate (probably 120* or greater) I could extract from the tank. When both of these are too cool then nothing will run and no reason to care about unwanted ghost flows. The key would be that the house loads would get first crack at the boiler water in the primary loop, then the barn's unit heaters, and finally storage.
I was going to use my 700' of 1.5 underground pex between home and barn as my primary loop but sending the hotest water from the boiler to the house first via pex makes me wonder if that is a good idea in the case of an overheat situation. I would not want to have to replace the underground pex! Plumbing to storage first would alleviate some of this concern, but probably give me cooler water at the water to air HX in the plenum when boiler is running. Question is how much cooler would it be. Unless I misunderstood, Heaterman did not see a problem with the "large" primary loop when we talked about it. Don L's system uses a small primary loop driving 2 more "primarys" but he has 3 locations to deal with. I could add a small primary loop in the barn and have another "primary" in the home similar to Don's but not sure if that is necessary. Anyone have thoughts on this? The basement of the home is located about 15 feet in elevation above the boiler and storage. This shouldn't affect pumping on a pressurized system but I wondered about expansion tank and air separator locations. I just want to do it right the first time.[/quote]
What I've heard of being done in some cases is to use the storage tank as a sort of giant sized hydraulic separator... Put a pipe at the top and bottom of each end of the tank (once plumbed together, stacked tanks can be considered as one big tank...) and pump hot in the top at one end, using the boiler pump and pull it out at the other with the house loop pump... If the house is pulling as many BTU's as the boiler is making, the water essentially goes straight across the top of the tank w/ minimal mixing. If the house is pulling less, the surplus automatically charges the tank. You could do the same thing with a big tee fitting at the top and bottom, but IMHO flowing through the tank might be better.... Essentially what this does is separate the house and other loads from the boiler - all the loads or the boiler sees is the tank. Aside from possibly taking a little longer to get heat when doing a total cold start, I think this is a really good way to deal with pressurized storage, as the tank gets the hottest water, but simply passes it on to the load when needed. You can then do copper or black iron between the tank and boiler, and pex from the tank outlets on. It also means that the loop from the boiler to storage should be short and low head so that one could use a small pump (I'd look at one of the temp responsive ECM pumps as that would allow ultra simple return protection as well)... Since the house loop then no longer has to deal with pumping through the boiler, (and the storage tank has virtually zero flow resistance) it might also be possible to downsize the house pump (and again look at some sort of speed control on that pump)
What I would do for expansion and air venting is put the main expansion tanks on the hot side boiler - storage loop, along with an air / dirt separator. I would put a second separator and possibly a small expansion tank at the highest point on the house loop. (The house loop could easily be a second PS loop or hydraulic separator setup depending on the nature of the house loads - but that is a totally separate design from the boiler / storage setup - essentially design it assuming you have a hot water supply and return pipe coming from "you care not where" and build around that...)
Gooserider
Gooserider[/quote]
That is the "hot" setup in my mind right now, although the "best setup" seems to change month to month with me as I learn new ideas.
Use the tank as the separator and if you have multiple pumps for loads you can use one tap on the tank and a manifold or multiple taps, one
for each pump.
Same on the charge side if you have more than one boiler. For fossil fuel boiler you can tie into the load side manifold so it will not heat the storage.
I'm sold...... now if I could only get a big tank in my basement![/quote]
Borrowed from another thread
On the subject of plumbing for loops that flow in opposite directions, there was a thread a while back with a lot of debate about how best to do it. It seems the easiest / simplest / least expensive solution that developed was to just have one length of pipe with two pumps in it that face opposite directions, and wired so that only one pump could run at a time... According to Taco tech support, obviously as long as one doesn't use flow checks, the flow resistance of a non-running circ is essentially negligible, so you just run one circ to pump into the tank for charging, and the other to pump out of the tank for discharging... It avoided the relatively high cost of the multi-way valves (in most cases the pump was less), and was a simpler thing to plumb than any of the loops with check valve approaches.
Gooserider[/quote]
Thanks for the tip, I will search for that link. I was so focused on the pumps with the inline check valves, my mind didn't consider that option. So when boiler is hot the tank will be charging, when the boiler circ is off (ie. boiler less than 140*) and the temp at top of storage is adequate (probably 120* or greater) I could extract from the tank. When both of these are too cool then nothing will run and no reason to care about unwanted ghost flows. The key would be that the house loads would get first crack at the boiler water in the primary loop, then the barn's unit heaters, and finally storage.
I was going to use my 700' of 1.5 underground pex between home and barn as my primary loop but sending the hotest water from the boiler to the house first via pex makes me wonder if that is a good idea in the case of an overheat situation. I would not want to have to replace the underground pex! Plumbing to storage first would alleviate some of this concern, but probably give me cooler water at the water to air HX in the plenum when boiler is running. Question is how much cooler would it be. Unless I misunderstood, Heaterman did not see a problem with the "large" primary loop when we talked about it. Don L's system uses a small primary loop driving 2 more "primarys" but he has 3 locations to deal with. I could add a small primary loop in the barn and have another "primary" in the home similar to Don's but not sure if that is necessary. Anyone have thoughts on this? The basement of the home is located about 15 feet in elevation above the boiler and storage. This shouldn't affect pumping on a pressurized system but I wondered about expansion tank and air separator locations. I just want to do it right the first time.[/quote]
What I've heard of being done in some cases is to use the storage tank as a sort of giant sized hydraulic separator... Put a pipe at the top and bottom of each end of the tank (once plumbed together, stacked tanks can be considered as one big tank...) and pump hot in the top at one end, using the boiler pump and pull it out at the other with the house loop pump... If the house is pulling as many BTU's as the boiler is making, the water essentially goes straight across the top of the tank w/ minimal mixing. If the house is pulling less, the surplus automatically charges the tank. You could do the same thing with a big tee fitting at the top and bottom, but IMHO flowing through the tank might be better.... Essentially what this does is separate the house and other loads from the boiler - all the loads or the boiler sees is the tank. Aside from possibly taking a little longer to get heat when doing a total cold start, I think this is a really good way to deal with pressurized storage, as the tank gets the hottest water, but simply passes it on to the load when needed. You can then do copper or black iron between the tank and boiler, and pex from the tank outlets on. It also means that the loop from the boiler to storage should be short and low head so that one could use a small pump (I'd look at one of the temp responsive ECM pumps as that would allow ultra simple return protection as well)... Since the house loop then no longer has to deal with pumping through the boiler, (and the storage tank has virtually zero flow resistance) it might also be possible to downsize the house pump (and again look at some sort of speed control on that pump)
What I would do for expansion and air venting is put the main expansion tanks on the hot side boiler - storage loop, along with an air / dirt separator. I would put a second separator and possibly a small expansion tank at the highest point on the house loop. (The house loop could easily be a second PS loop or hydraulic separator setup depending on the nature of the house loads - but that is a totally separate design from the boiler / storage setup - essentially design it assuming you have a hot water supply and return pipe coming from "you care not where" and build around that...)
Gooserider
Gooserider[/quote]
That is the "hot" setup in my mind right now, although the "best setup" seems to change month to month with me as I learn new ideas.
Use the tank as the separator and if you have multiple pumps for loads you can use one tap on the tank and a manifold or multiple taps, one
for each pump.
Same on the charge side if you have more than one boiler. For fossil fuel boiler you can tie into the load side manifold so it will not heat the storage.
I'm sold...... now if I could only get a big tank in my basement![/quote]
Borrowed from another thread
