TV ESBE By-pass Valve Piping


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Old 03-23-10, 02:07 PM
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TV ESBE By-pass Valve Piping

Gentleman,

I wanted you guys to take a look at a drawing for piping the Danfoss valve and I needed you guys to help me understand something. My plans are to pipe the valve on the return side and get the 140 degree model, to avoid condensation. From the diagram I can't understand how the boiler will keep from going into hi-limit before the system gets up to temp. The valve will not allow the boiler to receive any return water until it reaches 140. Will this work for a gravity conversion? There is a lot of water to heat up. Won't the boiler get up to hi-limit a lot quicker, since it is the same temp water going in plus whatever delta T the boiler loop is designed for? Would it get to hi-limit before heating up the system water?

system20piping1.jpg picture by ezra18042 - Photobucket
 
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Old 03-23-10, 03:08 PM
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The valve should modulate it position as the temp increases to have full flow into the system loop once it gets up to temperature.

The system should not go off on high limit with a valve such as this installed.

There are better more elegant ways to do what your doing, but this will get the job done well.
 
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Old 03-23-10, 04:46 PM
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Right... that TV isn't just going to 'pop' open at the set temp... it will open slowly as it heats up. The 'guts' of that valve are basically an automotive type thermostat.

Why are you thinking the boiler would go off on HL ? You'll have that set to something like 180 or so, right? So when the TV begins to open at 140-ish, it will start blending cool return water from the system... probably what you will see on the temp gauge is that it will rise fairly quickly to the 140 region, then as the valve slowly begins to open, the temp will 'hang' there for a while as the system rads and piping heat up... then it will sit around that temp for a while as the home heats up... and only if the heat call continues for a while will the valve then fully open and the water will get hotter.

Use a good quality GLOBE VALVE for the balancing valve. Ball valves are commonly used, but they are not the best choice. If you read the manufacturers specs, they are not intended to be used for 'throttling' applications.

I'm assuming yer gonna stay with NG... so the 140 is probably a good choice.

Are you planning any Outdoor Reset? You might have to consider the TV temperature when setting your BOIL MIN.

Looking at the drawing, I'm wondering if the system pump shouldn't be on the right side, pumping away from the boiler, and the air separator and expansion just upstream of that?

There are better more elegant ways to do what your doing
Substitute 'complicated' for elegant!
TO, what'd ya have in mind?
 
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Old 03-23-10, 05:51 PM
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Boiler bypass.
.
boiler control with ODR and above boiler bypass
.
PS piping with variable speed injection..

How mild or wild do you want it, I can dream up a million ways to pipe a boiler .

now for a Beer 4U2
 
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Old 03-23-10, 06:21 PM
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Old 03-23-10, 06:59 PM
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same as the original picture, just 2 more zones
 
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Old 03-23-10, 10:21 PM
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Yeah, except that one gots the pumps and tanks where I would rather see them...
 
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Old 03-24-10, 08:22 AM
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OK, I don't know why I was just thinking that the water temperature at return port was the only one that mattered when the valve reacts to the temperature in the boiler loop.

I'm assuming yer gonna stay with NG... so the 140 is probably a good choice.
Yes, sir!

Are you planning any Outdoor Reset? You might have to consider the TV temperature when setting your BOIL MIN.
I would love to, but I have no idea how to get it done and what parts to use. Maybe with your help I can. I would like to keep the system simple, cost effective and reliable. I wouldn't mind spending a little more money on something if it's going to help out in the long run.

Are those orange valves in the comfort-calc schematic, balancing or valves? Sorry, I'm not to familiar with the symbols for valves.

Use a good quality GLOBE VALVE for the balancing valve. Ball valves are commonly used, but they are not the best choice. If you read the manufacturers specs, they are not intended to be used for 'throttling' applications.
If I go with globe valves or any other balancing valve I would need temperature gauges on the return and supply lines of both the system and boiler loops correct?

I'm also planning on getting an indirect water heater for the house, so that's another thing I need to think about getting piped.
 
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Old 03-24-10, 09:55 PM
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Originally Posted by xiphias View Post
I'm dealing with the same situation as the OP. Why bother with P/S when he just has two high temp zones, and an indirect that will operate by itself? Seems like a great way to feed the power company. Haven't folks been skipping P/S forever with cast iron boilers systems, and not having problems with it? I'm not questioning the need for boiler protection bypass valve, just why go to P/S.

Another question: how to size the circulator for old gravity zones like this, especially if I'm going to use zone valves. Big iron pipe, undoubtedly corroded, and barrels of water. I understand that I need to move at least enough water to pull the BTU out of the boiler. But do I need to move more water than that? Can I just ignore calculating head loss, as there probably isn't much? Finally, would a constant pressure circulator and valve zoning make sense in this setup?

http://s3.pexsupply.com/manuals/1252..._PROD_FILE.pdf
 
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Old 03-24-10, 10:15 PM
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If you have high temp zones, why would you need boiler protection ?
The indirect will ramp itself up pretty quick.
Yeah a lot of the older piping methods seem to tax the grid pretty good.
I used to zone with circulators... not any more.

There really is a time and place for PS piping, and the installer needs to know it.

As for the piping, please don't confuse flow for flow velocity.
You will still move the same GPM thru 2 or 4 inch pipe, it will just require less power than trying to move the same flow thru 1/2" pipe or whatever. The flow is still there.
Actually your reynolds numbers just drop with larger pipe and you will end up with laminar flow. This is not really a bad thing in your supply pipes
 
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Old 03-25-10, 11:05 AM
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The reason for P/S with OP's application is pretty simple actually...

Yes, he's got barrels and barrels of water.

For boiler protection he is choosing to use the TV... so that when there is a heat call, no heat will get to the system until that TV begins to open, if NOT piped P/S... and when it DOES start to open, as soon as it does, the cool return water will quickly close it again... how many times will this happen until the TV is fully open and allows heat to the home?

By going P/S with the TV, you have full flow in the system from the start, and full flow in the boiler, and the boiler is protected... as soon as the TV begins to open, some heated water will flow into, and all the way around the loop... instead of just a little 'sneeze' of hot before the TV rocks closed again...

A bypass is definitely recommended for his application, and piping the TV this way is ideal for his situation.

If you have questions of your own that are not related to this thread, please start a new topic, rather than hijacking this one.
 
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Old 03-25-10, 02:47 PM
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Thank you Trooper! I guess everyone (BuffaloDIY) has there own opinion and choices.Now, back to the topic.

Is it best to go with full size on the bypass? The boiler that is going to be installed has 1.25" supply and return outlet.

I have ordered the TV already, but could only find it in 1.5". I figured a couple of reducing fittings couldn't hurt.

I have read that the IWH is better installed in parallel with the boiler loop instead of as a separate zone. What controls can be used to give the IWH priority and for summer time operation?
 
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Old 03-25-10, 03:54 PM
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Ezra, here is the 140 valve in 1-1/4" ... pricey lil buggers, ain't they? I don't know why the description says 85/140 though... but this is the one.

Patriot Supply - 065B8924

verification of part number:
065B8924

Personally, I don't like the idea of using the reducing couplings... it will work, but how bad it will look? If aesthetics matters... I think it does, but just my opinion!

Yes, I think the bypass should be full size.

I have been trying to get away from 'designing' systems, cuz I'm a fixer, not a designer (unless it's a control system, which you did ask about)... so hope that some of the other guys will chime in and make suggestions about that... I think there are some other good diagrams at comfort-calc that will fit your app.

You had asked about the 'yellow valves' in the drawing... those are boiler drains, but they are there for more than draining. One thing you need to consider when putting a system design together is "How am I going to fill the system, and vent the air?" ... If you look at that drawing, you will see that next to each one of those drain valves (more properly called 'purge valves') there is a shut-off valve. The idea is that you would connect a hose to the drain, and CLOSE the associated shut-off valve, and feed water into the system to fill it. At first, all you will get is air out the hose, but as the system fills, you will get water... when you get water, you know it's full. If those shutoff valves weren't there to 'route' the water into the system, it would take the path of least resistance and never fill the system up... so there has to be a 'roadblock' established to make the water go where you want it to go.

"Become the water and you will see..."
Zen and the Art of Boiler Maintenance
 
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Old 03-25-10, 04:17 PM
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BTW, have you done a heat loss? and what size boiler are you installing?

I know you may have said all this, perhaps in another thread, but it's probably a good idea to repeat it here...

How many zones?
How are you zoning, circs or valves?
If you are zoning with circs, will the indirect also be on a valve, or will it have a circ? (circ is preferred IMHO)

Answers to these will help get answers...
 
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Old 03-26-10, 08:31 PM
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Trooper, I know it wasn't not my first choice, but the price difference from 1.25" to the 1.5" was almost $53 and there is still a lot of material left to buy. If it was something that would diminish performance then I wouldn't trade that off, but I have to save the money for the important stuff.

BTW, have you done a heat loss? and what size boiler are you installing?
Yes, it came out to 79k. The boiler has a rating on 84k.

How many zones?How are you zoning, circs or valves?
I'm not planning on splitting into zones. The converted gravity system does have 2 return and 2 supply lines, but I just thought of keeping it simple. If I were to go with zoning, I would probably go with valves.

If you are zoning with circs, will the indirect also be on a valve, or will it have a circ? (circ is preferred IMHO)
I would use a circulator for the indirect and pipe ii in parallel off of the boiler loop.

BTW-I am going to use copper pipping because of the convenience of being able to cut it and not worry about having to deal with black pipe and the biggest factor, not owning a threading machine. If I did own one it would probably be a one time use thing anyway.
 
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Old 03-26-10, 08:34 PM
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Yes, it came out to 79k. The boiler has a rating on 84k.
I meant to write that the boiler has a rating of DOE of 84k.
 
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Old 03-27-10, 06:18 AM
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Originally Posted by TOHeating View Post
If you have high temp zones, why would you need boiler protection ?
The indirect will ramp itself up pretty quick.
Maybe boiler protection because of the high mass zones? It takes so long to heat up from cold, that maybe the boiler would operate at condensing temps for a while. As we improve to reduce heat loss in these old houses, the boiler gets smaller, but the mass of the old gravity heating system stays the same.
 
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Old 03-27-10, 07:15 AM
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Sorry for the earlier hijack.

Trooper: Trying to get my mind around this.

Regarding advantage of P/S for the OP's design, you write:
Originally Posted by NJ Trooper View Post
For boiler protection he is choosing to use the TV... so that when there is a heat call, no heat will get to the system until that TV begins to open, if NOT piped P/S... and when it DOES start to open, as soon as it does, the cool return water will quickly close it again... how many times will this happen until the TV is fully open and allows heat to the home?

By going P/S with the TV, you have full flow in the system from the start, and full flow in the boiler, and the boiler is protected... as soon as the TV begins to open, some heated water will flow into, and all the way around the loop... instead of just a little 'sneeze' of hot before the TV rocks closed again...
But earlier you write:
Right... that TV isn't just going to 'pop' open at the set temp... it will open slowly as it heats up. The 'guts' of that valve are basically an automotive type thermostat.
Aren't these conflicting? I think even for a simple parallel design, as the system warms up, the TV will slowly increase rate of cold system water entering the boiler. I don't see the coughing and rocking.

I see the advantage of P/S as simpler design for multiple temp zones and complex setups. When we're dealing with old style aspirated boiler and just two high temp zones and an indirect w/overide - seems to me that for the OP's setup could be simple. As long as we're 1) moving enough GPM to move the energy out of the boiler without exceeding 190F, and 2) we don't exceed design flow rates - then a simple parallel design might be the way to go. Hopefully this isn't just a matter of opinion - certainly the cost and energy savings of avoiding P/S are real. I'm a newbie though - very interested in all of your actual experience.

Has anyone actually had problems with a system like the OP's that is just simple parallel piping without P/S?
 
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Old 03-27-10, 09:16 AM
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Aren't these conflicting? I think even for a simple parallel design, as the system warms up, the TV will slowly increase rate of cold system water entering the boiler. I don't see the coughing and rocking.
Consider this scenario WITHOUT the P/S first: Starting from a cool system and boiler. TV is closed to the system, and there is a heat call.

Boiler fires up, circ runs and pumps 'most' of the flow through the TV. The boiler will heat up pretty quickly considering the volume of water it has to deal with at this point. There is next to no flow through the SYSTEM. Then, the TV slowly begins to open, but it's just a 'trickle' flowing into the high volume system.

Now, a few things begin to happen at the same time... cool water from the system flows into the TV. This will cause it to be cooled off, and either close completely, or perhaps stay open at that little trickle. There is still VERY little flow in the system itself, and the heated water that DOES get out into the system is going to heat the first rads in the loop ONLY. Since the water in the system is moving so slowly, the heated water that does get out there is going to cool again, because it is moving so slowly.

Meanwhile, the boiler probably is going to bounce of the high limit... but it will be protected... but very little heat is actually being transported into the system. Eventually, the system will heat up and the valve will open, but how long is that going to take? Add to that the fact that because of the very lazy flow in the system it will be extremely 'unbalanced'... the first areas on the loop will heat long before the last ones. Depending on the location of the thermostat, the first areas could easily overheat, and the last never reach setpoint.

Scenario 2: TV with P/S, piped as diagram. Heat call received, burner fires, boiler pump runs, there is full flow through the boiler. SYSTEM pump runs, and there is full flow ALSO through the SYSTEM. (this point is important!)

Boiler heats, TV begins to open slowly, releasing heated water into the system... and here's the difference... the heated water that is released is going to be pumped ALL THE WAY AROUND the loop. This results in the entire loop heating up at the same rate, rather than the beginning of the loop first... it will be balanced. The TV is still going to open slowly, but since the whole system is being heated at the same time, it won't be presented with water that has moved slowly through the system and had time to cool off again. Once the system begins to heat, the ENTIRE system begins to heat.

As long as we're 1) moving enough GPM to move the energy out of the boiler without exceeding 190F
That's just it... without the P/S piping, you won't be moving those GPM to the system and getting the BTU's 'out there'. Well... you will get them out there actually, but as explained, they will be dissipated very unevenly.

I guess the bottom line here is that with the TV installed without P/S piping, what you end up with is a SYSTEM bypass. Anytime a SYSTEM bypass is used, the potential for unbalanced heating is there. System bypass reduces the flow through the system, and it won't heat evenly and properly. The TV is STILL a system bypass, but the P/S piping and the extra pump counters the flow problem that is encountered. The price of a few tees, a pump, and the minimal electricity to run that pump is a small price to pay for a system that heats the home comfortably!

Has anyone actually had problems with a system like the OP's that is just simple parallel piping without P/S?
There was a thread here, in the last few months, that illustrated this exact problem. I don't think I'll be able to find it again, but it was this EXACT example.
 
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Old 03-27-10, 10:52 AM
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Aren't we missing a very important point. Even with the TV valve and p/s how often will the system even get close to 190. My guess is hardly ever. The more cast iron radiation the lower the system water temperature needs to be. P/S will help control the system water temperature even though the boiler is getting hotter. The flow through the boiler should not exceed 8 gpm and in all reality the system flow does not need to exceed that either. The indirect should be piped below (boiler side) of the thermostatic valve.
 
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Old 03-27-10, 12:54 PM
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I dunno if we're 'missing' it or not? I don't expect the system will ever get to 190 either... but that certainly isn't a bad thing, is it? Not sure if you are saying that it is or isn't? I _think_ you are saying it's a good thing, I should think it is...
 
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Old 03-27-10, 02:15 PM
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OK - I get the heat distribution issue. I ran the numbers to convince myself. The bypass initially will take 80% of the water (assuming 60F system, 160F output, 85K output, 8 GPM). So the system will only see 1.6 GPM, and that would probably heat the near boilers first. Also, looking atmospheric boiler install manuals, Weil Mclain at least recommends P/S. Thanks all.
 
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Old 03-28-10, 09:36 AM
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Originally Posted by rbeck View Post
The flow through the boiler should not exceed 8 gpm and in all reality the system flow does not need to exceed that either.
According to a chart "Sizing Circulators for Hot Water Heating Systems" written by Frank "Steamhead" Wilsey, it recommends getting a circulator with almost double the flow at about 3.5 ft of head, but this is based on the EDR of the system and because of the large volume of water in it.
 
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Old 04-05-10, 04:53 PM
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Originally Posted by BuffaloDIY View Post
Maybe boiler protection because of the high mass zones? It takes so long to heat up from cold, that maybe the boiler would operate at condensing temps for a while. As we improve to reduce heat loss in these old houses, the boiler gets smaller, but the mass of the old gravity heating system stays the same.
Not really worried about condensing due to mass, that is short term condensing that does little in comparison to low delta T, low return water temp condensing
 
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Old 04-05-10, 05:19 PM
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I think that's kinda what BDIY meant? perhaps he should have said high water volume, rather than high mass... although it's sorta the same thing.. the water is mass. And it's the high volume of water that would cause the extended periods of high DT and low temp return water... yes ? no ?
 
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Old 04-05-10, 05:30 PM
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EZRA18042,
If you flow more than 8 gpm through the boiler you will not heat the home and if you still can you will use more fuel. Again possible p/s piping. You only need to move enough water to match the heat loss. I would not use bigger pumps on a system with very little resistance to flow.

Yes Trooper.

TOHeating
The condensing time on a high water volume system may never stop condensing before the thermostat satisfies in the shoulder seasons.
 
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Old 04-05-10, 08:37 PM
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to clarify..

I would use a boiler bypass on a high water content boiler as that what it's for. This allows the boiler to get past it's condensing due to low boiler temperature.
Sure the return water is still cool but the delta T is high and flow is low.

That is what I was trying to imply
 
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Old 04-06-10, 05:17 AM
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rbeck,
I understand what you are saying, could it be that when the sizing circulator chart I referred to was published the author was not talking about a P/S set-up, but wouldn't the theory still apply? And how about I just go with a Delta T pump on the system loop, which will be the primary?
 
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Old 04-06-10, 06:44 AM
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TOHeating Yes I understand your point. I am a little thick at times. You are absolutly right. Decrease boiler flow and keep the flow in the system up without the second pump.

ezra18042
Yes that also works but you will need to have a valve on the supply side of the boiler before the tee on the p/s to throttle the boiler flow down to the proper flow. This is the same idea TOHeating is talking about except with a primary pump (variable speed) to maintain the system delta T. I am not sure what delta-T you would want at this point. If I had to guess I would say maybe 12 - 15. When you look at Delta-T charts the delta-T changes as water temperature changes. I would think the delta-T should be set at what it would be for the maximum water temp you need to heat with.
Let's say you have a heat loss of 80K and you have 888 sq ft of cast iron radiation. That means at design OD temperature you need a maximum of 140 water temperature. the 20 Delta-T charts shows at 140 your Delta-T would only be 10.
 
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Old 04-20-10, 01:32 PM
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one or two

Wouldn't I need 2 valves, one for the bypass and one on the supply line before the P/S tee?
 
 

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