Plumbing

[Bill322]

Wondering if anyone could help me with my plumbing issues? I have an central boiler edge 750 outside wood boiler I'm in need of some cost effective ways to re-plumb my system. As I'm not getting the btus required to heat my house. I am replacing my underground pipes with 1.25" thermopex this summer. Hopefulluy I've attached a photo of how it is plumbed now. Thank you Bill

 

[leon]

Wondering if anyone could help me with my plumbing issues? I have an central boiler edge 750 outside wood boiler I'm in need of some cost effective ways to re-plumb my system. As I'm not getting the btus required to heat my house. I am replacing my underground pipes with 1.25" thermopex this summer. Hopefully I've attached a photo of how it is plumbed now. Thank you Bill

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If you could flip that Jpeg. image that would be appreciated by many of us.

Changing to a larger pex is a waste of money. Your only going to get so many "BTU's out of each gallon of hot water" coming from your forest eater and your going to have even less cooler water BTU's to put back in the boiler on the return side.

You have three heat exchanger's pulling the heat out of that hot water when you should have only one in that rats nest feeding the zones and heat loads off a manifold.

I would lower you temperatures first before you waste any more money. You can heat with 160 degree water just like they do in Europe with pellet boilers. you do not need high water temperatures just proper cycling and hot burns.

Please invest in two paperbacks The first being Pumping Away and the second being Classic Hydronics written by Dan Holohan you can purchase them directly from the author at www.dansbooks.com

You will have a life time of knowledge at your fingertips with regard to how water heat.

 

[Bill322]

Hopefully I was able to flip picture

 

[hondaracer2oo4]

Leon, maybe a few more questions would be in order first. What is a forest eater, one of those old antiquated owb ? The cb and heatmaster outdoor gassers have gotten very respectabl numbers from the epa tests and although not as totally efficient as using them in conjunction with a large water store they do very well on wood consumption, open your eyes a little to the changing landscape of products. Ok I'm off my soap box.

What would lead you to believe he can run temps in the 160s for a high, what would his low be? Can you say condensation issues from low return temps? How about his house? How do you know his baseboard will put out enough btus running at those low emitter temps?

A waste of money with larger pex moving more btus per hour? What do you mean? He is maxed out at 7 gpm right now which isn't enough , at 1 1/4 he should be able to get about 11-12 gpm to the house which will increase his btus from about 70k to 110k. At 7 gpm he is currently not moving enough btus to the house to keep up with the two seperate boilers with two seperate flat plates. He needs to move more gpm to satisfy there demands

So he needs to bring more gpm and split them to the two boilers. What is the best way once he gets the gpm into the house to split it evenly? Is it a supple and return manifold with a hydraulic separator or something else?

 

[Dutchie84]

Some temperature readings in and out of the boiler, in and out of the house and all 4 ports on your hxs would help people on here give you some better advice.

I don't know how someone can tell you that you can run 160 degree water with out knowing anything about your heat requirements.

 

[maple1]

Given that we don't know anything about any of your flow temps (as mentioned above) or what you have now for underground piping & system pumping - your switch to 1.25" thermopex might be all you need to do.

('TV' = ?)

 

[Bill322]

Tv- thermostatic valve central boiler requires it. It closes and returns water to boiler if water drops to 150°. Underground pipes are 1"pex basically wrapped I. Styrofoam. Incoming temps around 178° outgoing 140-150.

 

[Bill322]

Running boiler @ 195°-185°
So definitely losing heat underground. Needing advise on how to plumb inside so to share flow equally between boilers

 

[leon]

I ran my "old" open firebox wood and coal Switzer boiler with an oil boiler as a back up with 160 high 140 low with a ten degree differential for 25 years before I switched to a coal stoker.

If you are growing grass in the pex trench from November to April that "is" a major issue.

Spend the money on those books before you spend any more money.

 

[nhtreehouse]

Needing advise on how to plumb inside so to share flow equally between boilers

While I'm no expert here, it seems you have multiple issues to solve. One is drastically reducing the loss underground - others have already covered that one.

Another issue appears to be a hydraulic balance problem. When the water leaves the "TV" block and heads east towards the tee, it comes to a decision point. To go straight through the tee to HX2 or out the branch port to HX1? Assuming the two HX are identical, the hydraulic resistance ratio between the branch and the straight-through port of the tee is about 6:1. That is, HX1 with it's 16 feet of piping is going to be much favored (lower resistance) over HX2 with it's 100 feet of piping. Hydraulic resistance is proportional to the length of the pipe. If the pipe size of the two runs is identical, the ratio of hydraulic resistance would be approximately 100/16 = 6.25. Given a known delta P at the right-hand side of the TV block, you could expect the flow in the two HX circuits to be around 6 times different.

With the given diagram, I would expect HX1 to provide plenty of heat, and HX2 not enough. What is your experience?

In theory you could add a balancing valve in the HX1 piping to increase it's hydraulic resistance and force more flow through the HX2 path.

As always, your mileage may vary.

 

[Bill322]

While I'm no expert here, it seems you have multiple issues to solve. One is drastically reducing the loss underground - others have already covered that one.

Another issue appears to be a hydraulic balance problem. When the water leaves the "TV" block and heads east towards the tee, it comes to a decision point. To go straight through the tee to HX2 or out the branch port to HX1? Assuming the two HX are identical, the hydraulic resistance ratio between the branch and the straight-through port of the tee is about 6:1. That is, HX1 with it's 16 feet of piping is going to be much favored (lower resistance) over HX2 with it's 100 feet of piping. Hydraulic resistance is proportional to the length of the pipe. If the pipe size of the two runs is identical, the ratio of hydraulic resistance would be approximately 100/16 = 6.25. Given a known delta P at the right-hand side of the TV block, you could expect the flow in the two HX circuits to be around 6 times different.

With the given diagram, I would expect HX1 to provide plenty of heat, and HX2 not enough. What is your experience?

In theory you could add a balancing valve in the HX1 piping to increase it's hydraulic resistance and force more flow through the HX2 path.

As always, your mileage may vary.

Yes HX1 has enough heat and HX2 can not keep up when it's real cold and all pex is 1"

 

[nhtreehouse]

Correction:

I believe the hydraulic resistance is correct, but the flow through the two HX is in error. I did some math on 6 gpm into the tee and come up with about 4.5 gpm through the favored HX1 and 1.5 gpm through the less favored HX2. Still a big difference.

My background is in electrical engineering - hydraulics is different - the "current" is raised to the 1.75 power. Ohms law is so much more straightforward!

Hope that helps...

 

[leon]

Correction:

I believe the hydraulic resistance is correct, but the flow through the two HX is in error. I did some math on 6 gpm into the tee and come up with about 4.5 gpm through the favored HX1 and 1.5 gpm through the less favored HX2. Still a big difference.

My background is in electrical engineering - hydraulics is different - the "current" is raised to the 1.75 power. Ohms law is so much more straightforward!

Hope that helps...

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Meh,

They have not lived until they had to live with 6 volts of line drop per mile with 4,160 3 phase 60 cycle.

 

[hondaracer2oo4]

I have talked to Bill in the past about this issue so I do have some prior knowledge of his issue so he can clear up some of my facts here but he did test the GPM by disconnecting the return line at the boiler and filling a bucket. He came out to 7 GPM. So we know that the system is getting 7 GPM through it. We knew his HX2 which is the boiler on the old side of the house which needs more BTUs than HX1 which is feeding a boiler in a new section of house. HX2 is getting less gpm which is confirmed by the large temp drop across the HX. Bill has tried to "balance" the flow in a crude manor by gating back a ball valve going to HX1. This brought is Delta T across HX2 up into a usable range but not enough was getting to HX1 at that point and he had a large Delta T across that HX. So ultimately we know that he just plain isn't getting the GPM through the system that he needs to maintain and adequate Delta T. This brought us to the conclusion that he simply needs more GPM to the system and being at 1 inch pex now which maxes out around 7 gpm, he needs to move to 1 1/4 to get around 11 gpm through the system. So if he brings 1 1/4 into the basement, what is the best way to balance the flows to achieve an equal flow?

 

[hondaracer2oo4]

Would a balancing valve on both supply lines going to each boiler in conjunction with the 1 1/4 supply from the boiler be the easiest and least expensive way to split the gpm between the two boilers?

 

[maple1]

Shouldn't a tempering valve be next to or at the boiler?

Manually balancing via ball valves would likely be the cheapest & easiest, but would likely require a lot of fiddling with.

Still don't know much about the pumping of this system. HX sizes? Kind of thinking there should just be one big HX in the house. Then maybe a primary/secondary setup or supply/return manifold setup with each boiler drawing heat as it needs, with it's own circ & call for heat.

 

[hondaracer2oo4]

Tempering valve for what purpose?

He could use a 100 plate hx in a primary loop when it enters the house from 1 1/4 thermopex. Then he could ditch the two flat plates st each boiler and just have them draw off the primary loop as secondary loops when each boiler calls for heat. He would need a whole lot of new parts for that, 100 plate hx, 1 1/4 copper for a primary loop, pump to spin water around the primary loop, a pump for each secondary loop to each boiler, copper or o2 barrier pex to get the secondary loops to the boilers etc. lots of money and work.

I think a workable system could be accomplished with balancing valves although I have never used them and don't know exactly how they work, anyone have expierence?

 

[Bill322]

Shouldn't a tempering valve be next to or at the boiler?

Manually balancing via ball valves would likely be the cheapest & easiest, but would likely require a lot of fiddling with.

Still don't know much about the pumping of this system. HX sizes? Kind of thinking there should just be one big HX in the house. Then maybe a primary/secondary setup or supply/return manifold setup with each boiler drawing heat as it needs, with it's own circ & call for heat.

Right now I'm running a grundfos 26-96F was running a taco 2400-20 but was making all sorts of noises so switches it out. Circulator is at boiler. Each HX is 40 plate but I believe they are from China so don't know how efficient they are

 

[hondaracer2oo4]

Bill, I run a 50 plate cheap exchanger and it seems to be just fine. They are simple devices, I think as long as the. Number of plates are there they should all perform pretty close. Have you been able to balance the ball valves so that the second hx has a reasonable delta t across the hx while the number 1 hx can keep up with demand on that side of the house even though the delta t may be more?

 

[Bill322]

Bill, I run a 50 plate cheap exchanger and it seems to be just fine. They are simple devices, I think as long as the. Number of plates are there they should all perform pretty close. Have you been able to balance the ball valves so that the second hx has a reasonable delta t across the hx while the number 1 hx can keep up with demand on that side of the house even though the delta t may be more?

Not yet haven't had time and it has warmed up again so it's really hard to determine what's going on as the house heats just fine currently 50°

 

[maple1]

Tempering valve for what purpose?

Sorry - thermostatic valve. As mentioned above - 'TV'.

 

[Bill322]

Tempering valve for what purpose?

Sorry - thermostatic valve. As mentioned above - 'TV'.

Central boiler requires a TV so if the OWB loses temp it close and sends water back to boiler it works kind of like a cars thermostat. It starts to open @ 170° and fully open @ 175°

 

[maple1]

Right now I'm running a grundfos 26-96F was running a taco 2400-20 but was making all sorts of noises so switches it out. Circulator is at boiler. Each HX is 40 plate but I believe they are from China so don't know how efficient they are

Only one circ? It's at which boiler? Not sure how you can get something to work here with only one circ.

I don't think a whole bunch of new parts would be needed to go to a manifold setup with a circ for each boiler. You would need a circ for each boiler - circs are in the $100 range. But seems to me each boiler should have its own circ anyway now? If you didn't want to spring for a new big HX, you could use the ones you have in series. Would be some work re-plumbing, but I'm not seeing a whole bunch of new parts being needed.

Still missing pieces here...

(What is 'temp' in the diagram?)

 

[maple1]

Central boiler requires a TV so if the OWB loses temp it close and sends water back to boiler it works kind of like a cars thermostat. It starts to open @ 170° and fully open @ 175°

Right - my question was, shouldn't it be right at the boiler instead of inside at the end of your underground loop?

 

[Bill322]

Right - my question was, shouldn't it be right at the boiler instead of inside at the end of your underground loop?

It's requires to be in building being heated. Temp means temp gauges. The circulator is outside @ wood boiler. I was wondering if a 1.25" copper manifold would work with 1" tees and a circulator for each boiler. But would that balance the flow to each boiler?