BB piping too small - Replace, Rezone, or Both?

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Old 07-21-08, 01:58 PM
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BB piping too small - Replace, Rezone, or Both?

After a few winters during which I've had to supplement my heating system with use of a wood stove and/or portable electric radiators, I've come to the conclusion that the 1/2 PEX tubing supplying the entire 88 feet of fin-tube baseboard in the first floor of my 1890 two-family home is woefully inadequate. My question up front is this: Would it be more effective to split the single loop into two (or more?) zones or to replace the 1/2 tubing with 3/4?

Here's more detail if you have a couple of free hours:

We live in central New England in the first floor of a two story farmhouse built around 1890. During the first winter after we moved in, we had a few nights when the house got down to the upper 50's despite the setting of the thermostat. Fortunately, the house had a wood stove (and now we knew why) so we were able to use that on nights that we knew it was going to get below about 20. After that winter, we had cellulose blown in to the walls which did help a bit. Now the heating system can maintain upper 60s until it gets down below 15. Below that, it'll start to lag and drop to the low 60's. Certainly not as bad as before, but still not good.

The house has about 88 feet of fin-tube baseboards in a single loop mostly on exterior walls. However, the piping between the baseboards is 1/2" PEX. A plumber who was there doing annual maintenance on the boiler said that the tubing was severely undersized for that length of loop. The boiler is a relatively recent Burnham spirit boiler that also heats a Super-Stor water tank. The boiler doesn't seem to run excessively even when the inside temp is way below the thermostat setting. I assume that's because the water is already at its max temp and there just isn't enough of it moving through the baseboards.


The two options I've been considering are:
1) dividing the loop into two or more separate zones
2) replacing the 1/2" PEX with 3/4" PEX.

Originally, I was leaning towards dividing the loop into more zones and adding thermostats for each. I liked this because it would allow us to heat only the spaces we were using. There's one room that is a terrible energy sink (hot in summer, cold in winter). It was part of a somewhat poorly constructed addition back in the early 1900s that has a flat roof and nothing above it unlike the rest of the 1st floor. I wanted to be able to keep the heat much lower in that room, but still protect it from freezing. I also wanted to have a zone for day time vs. night time spaces to save energy.

As it turns out, we're going to be moving out of that unit and renting it out. With that in mind, I'm hesitant to make the heating system more complex. The additional control that I'd appreciate with multiple thermostats might annoy, confuse, or at least be lost on tenants who are less interested in maximizing the efficiency of heat use. Also, I've got about 12 months worth of projects to complete in the 3 months we have before renting the place and it seems like that is the more complicated solution. Now I'm leaning towards just replacing the tubing.

So my questions are: Is it probable, possible, or a long shot that replacing the tubing would allow the heating system to keep up even when the temps are in the single digits?

Would it still make sense to just go for it and divide up the loop into zones?

Is it worth doing both?

Am I a lunatic for considering doing the work myself?

Thanks in advance for any thoughts!
 
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Old 07-21-08, 03:16 PM
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Without doing a proper heat loss calculation on the house it is impossible to state with any degree of assurance that the installed 88 feet of baseboard convector is sufficient to keep the house at the desired temperature.

HOWEVER, whoever piped that system with 1/2 inch PEX should be shot. I have very little experience with PEX but that system should have nothing less than 1-inch PEX. You could probably get by with using 3/4 inch PEX if you also added zoning but you are correct about the possible pitfalls of using multiple zones with renters.

And no, I don't think you are a lunatic for considering to do the work yourself. I would suggest that you understand the necessity of avoiding air pockets (much harder to do with PEX) when running the piping and the different methods of attaching fittings to PEX. The time tested method is the Wirsbo/Uponor method and that is what I would use. The tools are definitely expensive but you do not want any failures in this system, especially with a rental. Whatever method you use be sure that all components (tubing, fittings and tools) are compatible, preferably from the same manufacturer.
 
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Old 07-21-08, 04:05 PM
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Are you certain that all other things are in order ? for example, is the circulator pump working properly ? that there is no air trapped somewhere in the loop ?

what furd said ... I'm gonna elaborate on the first paragraph a bit because I feel that needs to be understood ...

First, 'standard' fin tube baseboard is capable of around 550 BTU/FT of heat emission. So, 88 feet of installed X 550 = 48,400 BTUs available to heat the home... no matter how big the boiler is, or how much water you pump through it, that's what you have to heat the home.

HEAT LOSS: You've done all the right things as far as attacking the problem, by first insulating and sealing, etc ... I suggest that you continue to do that. New windows and doors would help a great deal also, because in addition to heat loss through the walls, you probably have a lot of infiltration of cold outside air.

But, if the building is losing heat faster than you can replace it, it will cool down ...

I agree that 1/2" for that run is ridiculous... it's further limiting the output of the BB by restricting the flow.

Since the flow is restricted, it's a very good bet that the baseboards near the end of the loop are pretty cool ... the water has lost most of it's heat coming around ... so, the rooms on the end are likely to be even cooler ... and, since the return water is pretty cool, it's also opening the door to flue gas condensation problems in the boiler itself. The water needs to return to the boiler around 135°F for this NOT to occur. (that's for GAS fired, I believe OIL fired is less, but plan on 135 minimum)

I would split it ... and run 3/4 (I believe the capacity of copper is slightly higher than PEX, and that is why furd suggested 1" PEX ... but the baseboards themselves are 3/4" correct ? )

So here's what to do ... get as close to the midpoint of the loop and cut it there, run a 1" SUPPLY and feed both sides at that point. Where the old supply and return are, join them together and run 1" from there back to the boiler RETURN. (I don't think using a 'bull' tee (i.e. feeding the center of a tee and taking off the loops from the sides) at this point is a good idea ... I would use a 'manifold' ... 1"x3/4"x1" tees, in a line, and the two loops feeding off the 'taps'... Grady ? furd ? anyone ? is that right ?

1" is big enough to feed two loops with the correct flow.

Do this before you start replacing the 1/2" sections BETWEEN the baseboards. Try it for a winter and see what happens ... oh wait, you won't be there next winter ...

If you wanna get some concrete evidence as to whether or not you have enough baseboard installed, go to www.slantfin.com and download their heat loss software ... do a room by room heat loss calculation and the program will tell you if what's installed ain't enough ...

What boiler ? how many BTU ? gas or oil ? etc ...
 
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Old 07-21-08, 04:30 PM
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Thanks for keeping me honest, Trooper.

As for that 550 BTUs per foot figure...That is at a design temperature of 180 degrees and for "standard" finned tube. There is a high output finned tube that has a bit more output, I think it may be as high as 750 BTUs per foot but I don't remember. You can also increase the output by increasing the temperature but when using PEX I would rather go with more length and lower temperatures than the other way.

Yes, copper will have a higher BTU capacity size-for-size than will PEX because the internal diameter of PEX is a bit smaller than the same nominal size of copper. I wouldn't be too concerned about the tee in Trooper's plan (which is a good one, btw) but I would want to have balancing valves on each branch, preferably on the returns and ideally something like Bell & Gossett circuit setters. I would replace the 1/2 inch PEX connecting the various baseboards to each other although 3/4 inch PEX would be fine for this part.

By increasing the size of the "connectors" between baseboards you will have the ability to flow more water through the system. I'm betting your boiler is way oversize for the amount of baseboard installed and flowing more water will keep the return temperatures up and minimize the condensation at the returns point of the boiler. Having the balancing valves will allow some control over the flow and also the return temperature.
 
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Old 07-21-08, 04:55 PM
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me keep furd honest ? datz funny ...

I've found a few manufacturers of higher output baseboard, but dumb me didn't save the links ... if you search around some, you will find them.

If you have a 'problem area' you could also probably replace with some commercial stuff that has double (even triple) runs of fintube in the cabinet... bigger yes, but if it solves a problem, well... or panel radiators ... there's some nice ones out there ... or even a convector cabinet.

but all that is only if you find out that you don't have enough installed emitters to match the loss. That's where the heat loss calcs come in ...

Something else to think about ... make sure that there is at least 2" of clear opening on the bottom of the baseboards. If there's carpeting installed, it can limit the airflow through the unit, ALSO cutting down it's BTU output... in fact, anything that cuts down the air is gonna hurt it ... big furniture, etc ...
and, when was the last time the baseboards had the covers off and the fins brushed and vacuumed ? cuz you would be amazed what a coating of dust can cut down ! every little bit helps when yer cold !
 
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Old 07-21-08, 05:23 PM
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Can I jump in on this one for a minute?

Everything you guys have been saying is fine


Except...

Before you condemn the use of 1/2" piping, (which I have never done, but have thought of doing it), To my knowledge, and if you think about it, The proper design temp for the return temperature is 20deg below the feed temp. Most circulators today move water faster than they should and that temp number is usually much closer than it should be. So if you can still maintain that 20deg differential from feed to return while the system is in operation, you have accomplished what you are trying to do, no matter what size the pipe is.

I do know of a few jobs that were piped in 1/2" piping and never had any problems.

I think the problem here is a multiple one. The heat loss of an older home is usually much greater, and is there even enough baseboard for the home? Also, is the boiler running at 180deg ? I would be looking at these issues before repiping the system.

If I am wrong, let me know, because this is the way I understood this is how it works. Maybe I misunderstood something.
 
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Old 07-21-08, 06:17 PM
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right Mark!

that's why I suggested not attacking the 1/2" sections between the baseboards just yet.... but that splitting the loop in half and feed it with 1" supply and return would go a long way to getting good flow through that long loop.

66' I think is the max one should use on 3/4", and he might find that 44' is fine for 1/2" ...

especially if the bulk of the piping IS actually 3/4" fin tube ...

might be OK actually ...

but there still could well not be enough radiation, depending on the heat loss ...
 
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Old 07-21-08, 06:41 PM
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Burnham Spirit SP4N

Wow. Thank you all for the great replies. This info is extremely useful. I've been reading through
Modern Hydronic Heating for Residential and Light Commercial Buildings trying to figure out what the best course of action would be, but my day job keeps getting in the way.

At any rate, the boiler is a 96000 BTU/h Burnham Spirit 4N direct-vent boiler. I've taken a couple of pictures of the connections to the boiler as well.

http://www.nedr.com/gallery/main.php?g2_itemId=4996

I need to do some measuring to calculate the heat loss with the Slant Fin software. My first roughly-estimated try came out to about 30K BTU/h. Our unit is about 1400sf, and most of the windows are double glazed. The convectors themselves are 3/4" and very probably cheapos from the local BORG.

It seems like there's little downside to refitting with 3/4" PEX as a first step. Maybe that and some sealing will take care of it and I can move on to the avalanche of plumbing issues in our "new" (uh, 1890 again) place.

Thanks again for the replies. This is a great board.
 
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Old 07-21-08, 07:21 PM
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Just a few more noticeable items

It looks like the circulator for the heating is a 009 or 0010, not even a 007, so I think that may even help more with the 1/2" pipe situation. I am not an engineer so I could be wrong.

And that pex connection looks terrible. It looks like it might have some stress on it or the pipe was not cut straight. It may never be a problem, but if redoing any piping, I would redo that joint.
 
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Old 07-21-08, 08:26 PM
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If the space heating circ is a 009, then the 1/2" pex has to go. Splitting the zones would help, but without more specifics e.g., what furd listed, my kneejerk reaction is this system needs a ground-up evaluation. That is an electricity sucking, high head monster needed to overcome the high head of a much-too-long run of 1/2" piping. If it's a 0010, then it's a wonder the system flows at all. It's a low-head, high-velocity pump.

Agree with the others' advice regarding priorities and things to check before starting to replace the 1/2", but if that's an 009 (or even 008), then that's a good clue the original installer hadn't a clue and just started adding a bigger pump until the system flowed water.
 
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Old 07-21-08, 08:56 PM
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Ohhhhh... I completely overlooked that you said it was run in 1/2" PEX ! I can look better than I can read I guess ! I was assumpting it was an old system run in copper ... bad me.

Yeah, replace the PEX...

say, do you know if the PEX is even the right type ? What does the imprint on the tubing read ? It's got an O2 barrier, correct ?
 
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Old 07-21-08, 09:15 PM
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On the supply and return manifolds, is the first tap bigger than the second two ? i.e. one 1" and two 3/4" on each mani ?

And one of them is capped, while the other is used as a connection for the makeup water ?

Maybe you could use those two larger take-offs instead of the smaller one ... move the pump over, mount with bigger pipe (1") and split like I said in earlier post ...

You could re-pipe the makeup water by removing the exp tank, install a couple nipples and a tee there, and connect the makeup water at that point in order to free up that take-off on the manifold.

Tell us the final results of the heat loss ... 30K BTU sounds kinda low for that vintage building ... is the second floor occupied/heated ? If not, and there is no insulation in the ceiling, you might be losing quite a bit of heat there... I think you can change the factor for the ceiling under un-heated space. But still, if it's anywhere close, then you may have enough baseboard already, and re-piping could solve the problem.
 
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Old 07-21-08, 09:22 PM
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by the way... if those take-off ARE different sizes, the indirect probably should have been on the larger one from the git-go.

Is the indirect piped in 3/4" ? Probly should be 1" ... what size indirect ?
 
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Old 07-22-08, 08:01 AM
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Indeed, the circ for the heating loop is a Taco 0010-F2 and the circ for the indirect is an 007-F5. On both the supply and return manifolds, the first tap is bigger, 1+ inches and the other taps are 3/4. However, the first tap on the supply side is just capped. Both the indirect and the heating loop are on the 3/4 taps. The big tap on the return side is reduced to 1/2 and appears to be the makeup water connection.

Here's the info printed on the 1/2" PEX:

WIRSBO-hePEX SDR9 PEX-a 100PSI 180deg F / 80PSI 200deg F ASTM F876/F877 ICBO ES ER5143 ER4407 HAUSER UB 19971110 NOT FOR POTABLE WATER 001707

The boiler is gas, BTW and the water is at 180deg F. I'm not sure if I answered those earlier.

Doh! I didn't check the size of the SuperStor. Our unit has one full bath, a dishwasher, a washing machine, and a kitchen sink as hot water loads. I only recall running out of hot water in the shower maybe once. The dishwasher and washing machine had probably been running around the same time. In fact, I think it was probably a little over-sized since the washing machine is shared with the 2nd floor. We supply the hot water, they supply the electricity for the dryer.

I forgot to add that I also added the insulation to the entire loop (except the last 4' at the cool end) and relocated the runs away from the sill. It had been mounted, uninsulated, directly to the sill plate for probably 30-40' of the run. That was one winter after we did the cellulose insulation and it did make a difference mostly in the rooms towards the end of the run.

I did think that 30K heat loss was a little low, but we do have good windows and the whole unit except for one room is under a heated 2nd floor.

From some of your comments, it looks like the 0010 circ pump fighting against the 1/2" PEX might be one of the bigger problems.
 
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Old 07-22-08, 11:16 AM
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Using smaller diameter piping to increase the temperature differential between supply and return is insane. The smaller piping will severely limit the heat flow and the more powerful pump required will use more electricity.

I strongly urge you to get rid of that 1/2 inch PEX and also get the proper pump. If you end up with a 3 degree differential from supply to return (you won't) it will still be a better system. The 20 degree differential number is a maximum differential and not the minimum.
 
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Old 07-22-08, 11:48 AM
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Nobody said they were using the 1/2" pipe to change the differential temperatures.

I agree that a 3 degree differential is much better, But I was also always taught, that the IDEAL differential is 20deg and that is why we used to put in balancing valves. I have never been able to get a 20deg diff. without severely throttling down the loop. So if you can stay within your proper differential range, the size of the pipe is not a consideration.

If you look at this chart, the difference between the 007 and 0010 is in the GPM/flow not in the head. So if you do not exceed the head pressure, what is wrong with this circ.?

http://www.taco-hvac.com/uploads/Fil...CurveChart.pdf

So I don't see how this can hurt. Am I blind?
 
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Old 07-22-08, 12:40 PM
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I just ran through the exercise of sizing a circulator pump in this document - http://www.taco-hvac.com/uploads/Fil...irculators.pdf.

I used 550 BTU/h x 88' to come up with 48400 BTU/h. Putting that into the formula flow = heat transfer/(500 * temp drop) gives me 4.84gph for a drop of 20 deg f.

The head loss calculation is a riot. With 1/2 PEX, the head loss came out to 133 feet. That's way off the sizing chart.

It looks like the 0010 is not terribly far off if I switch it to 1" PEX or 3/4 cu. After going through the rest of the calcs, I came out with a head value of 8.9 feet. 4.84 gph with 8.9 feet of head lands just about exactly on the chart for the 007, but it's not too far below the 0010. It almost makes me wonder if the person who installed the system was just off by a decimal point in one of the variables.
 
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Old 07-22-08, 01:28 PM
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No, nobody stated they were using the 1/2 inch tubing to obtain a certain differential temperature but someone (I'm too lazy to look back) was using the differential temperature to justify the use of the 1/2 inch tubing.

Heat flow is a complex subject and I don't completely understand all of the ramifications. The point I am trying to make is that by using the smaller tubing you are severely limiting the flow rate at any specified pressure. The energy used by the pump is also complex but a combination of high head and high flow equals high energy. Granted that this particular system has a high head because of the minimally sized piping it follows that to obtain a high enough flow rate to minimize the differential temperature (which allows all the convectors to "see" the same temperature of water) a higher than desired energy input to the pump is required.

By lowering the head of the system (by installing the proper piping) you will reduce the energy input to the pump. You will also lower the differential temperature of the heating loop and THAT will cause the convectors to emit a more even (and likely a higher rate) heat.
 
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Old 07-22-08, 02:49 PM
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So I think I'm settled on replacing the piping for the loop. That seems to be a reasonable task for my first foray into hydronic heating maintenance. My last questions are about the procedure of working on the system.

Can I drain the heating loop without draining the entire boiler?

Is it ok to allow the boiler to run while doing work on the heating loop? (with the heating loop disconnected and both ball valves closed)

Provided the answer to both of those questions is "Yes" here's the order of operations as I understand it:

1) Turn off the boiler
2) Drain the heating loop using the spigot above the ball valve on the return end of the loop
3) Close the supply & return valves on the heating loop
4) Disconnect both ends of the heating loop
5) Turn the boiler back on (to enable heating the indirect)
6) Run the new piping
7) Turn off the boiler
8) Connect the ends of the heating loop to the supply & return lines

After this, I'm not quite sure of the order of operations.
 
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Old 07-22-08, 04:02 PM
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One other thing that should be mentioned... VELOCITY of the water. Sure you can get 4.5 GPM through 1/2" pipe with a big-a55 pump, but the problem will be (not to mention extra electricity use) that the VELOCITY of the water in the piping will probably cause noise ... and possibly premature failure of the tubing/piping due to the 'scouring' effect of high speed water inside the pipe, causing pinholes... might not see it for years, but when/if you do, be prepared... so that's probably the main reason not to go with a huge pump and undersized tubing.

Figure on maybe 2.5 GPM (tops) for 1/2" pipe, and say 4 GPM for 3/4" (you could push it to 5) ... now, let's say that we round up your 4.84 GPM to 5 GPM ... so you need to flow 5 GPM to get the rated output from your baseboards ... if you split this into 2 parallel loops, each 1/2", wouldn't that be 5 GPM at 2.5 GPM per side ?

A handy 'rule of thumb' is 10000 BTU per GPM flow .

Even if you switched everything to 3/4", your loop is still technically too long, with 3/4", you should shoot for about 66' max ... 66' X 550 = 36300 BTU ... if you use 600 BTU/ft, it's right at 40000 BTU ... so you would need to flow 3.63-4 GPM in a 66' loop to get rated output. That's what they shoot for anyway.

If you split that loop with 1", AND switched to 3/4" on the loops, that would be great... you could EASILY get the flow you need.

If you need to run the boiler for domestic hot, AND you can valve off the heating loop, I see no reason that you can't run it while doing the work...

You're gonna have a hard time draining that heating loop using the valve on the return. There's no place for air to get in, so water can't come out. The drains on the returns are for PURGING the system upon initial fill (or after any re-work). You would close the ball valve on the return, hook up a hose to the drain, and open the water feed valve. This would force water through the boiler, up the supply, through the loop, and out the drain....

You would want to valve off the loop BEFORE draining it ...

Don't forget that you have an automatic water feed on there, so if you were to leave the valves to the loop open, and open the drain on the return, water would be fed IN at the makeup connection, across the header, up and OUT of the valve.

Can you take some more pics ? some from a little further back, showing any other drains etc ...
 
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Old 07-22-08, 04:22 PM
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Ya know, it's too bad there's not TWO 1" takeoffs on that manifold ... the indirect should probably be on 1", and I think that 0010 pump would be a good choice for that. If you do end up splitting the loop with 1", you don't really have a place to connect it, although I doubt that itty-bitty length of 3/4" would hardly be noticed by the system.
 
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Old 07-22-08, 05:42 PM
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Here's what I would do

1) split the system into two zones. You could do this using one thermostat or two for control. Your choice.

2) repipe the space heating loops in 3/4" PEX or 3/4" copper. Your choice.

3) repipe the headers so that the 1" is used for the indirect. Check the manufacturer suggestion for pump sizing. Chances are it's not an application for a 0010.

4) Sell the 0010 on craigslist for $25 and get the right pump for the indirect.

5) use the existing 007 for the space heating loops. Buy a Taco ZVC-403-EXP with two space heat circuits and one indirect. Pick up two Taco 500 series zone valves, too.

6) get a Taco PC-700 reset control. Run partial reset on the space heating and set the indirect for priority.

Done!
 
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Old 07-22-08, 06:35 PM
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Originally Posted by plumbingods View Post
If you look at this chart, the difference between the 007 and 0010 is in the GPM/flow not in the head. So if you do not exceed the head pressure, what is wrong with this circ.?
The problem is that the head (resistance to flow) of the 88 ft of 3/4" fin-tube, PLUS [however many] feet of 1/2" PEX, PLUS [however many] fittings far exceeds the rating of these circulators.

For example, at 15 ft of head, both the 0010 and 007 pump zero gpm. They are at what is known as "shut-off head." There is so much resistance in the piping that the pump is not capable of moving water through it.

Smaller diameter piping = higher head for an equivalent length. Try an experiment: get a 3" long hypodermic needle and try to blow air through it. Now get a piece of 3" long 3/4" copper pipe. Which is easier?

The 0010 is for higher-gpm, lower head applications. The 007 is for more "typical" applications. Compare the flow rates at 5 ft of head. At 5 ft of head, the 007 produces about 16 gpm. The 0010 produces about 26 gpm.
 
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Old 07-22-08, 06:39 PM
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hamhands: nice job digging up and using that Taco sheet to do the head and flow calc.

As Trooper says, shoot for about 2-4 ft/sec in your piping. 3.5-4.5 gpm in 3/4" copper and/or pex should be fine. There is considerable room to maneuver here.
 
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Old 07-23-08, 09:41 AM
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I've added some more pics as well as my first crack at a schematic.

http://www.nedr.com/gallery/main.php?g2_itemId=4996

I'm not sure if I have all of the symbols right so I added text for many of the elements.

I wonder if one of the reasons the piping was done with PEX is that the rim joists/sills on the house are huge timbers. There actually isn't a separate sill plate. It's just big 12x12 timbers laid on top of a brick wall that's on top of a pile of rocks. With this being the case, they had to drill diagonal holes up through parts of the timbers to get to the points at which the convector connections landed near the interior walls on the first floor. It might've been impossible to wrangle rigid cu connections through the holes. No idea if this was the case, but just a thought.

The next tricky thing is that I can't seem to find any 3/4" cu to 1" PEX connectors. If I can't find those, I guess I'd have to sweat my own together out of a 3/4" cu to 1" cu connector and a 1" cu fitting to 1" PEX adapter.
 
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Old 07-23-08, 04:32 PM
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I need to compare the schematic to the pics... there's a few things that look weird to me ...

1. your diagram shows 1/2" supply cold to the superstore ... really ? why would they feed the heater with 1/2", then take 3/4" on the hot outlet ? That's just plain wrong if it's so...

2. you are showing 3/4" between the return mani and the boiler, I'm pretty sure that's a typo ... cuz the pics clearly show 1-1/4" black iron ...

3. referring to the pics... as I suspected, they used reducing fittings on the superstore to drop the 1" down to 3/4" ... that's wrong... they shoulda piped 1" to the water heater.

4. there is an ARGO (I think it's Argo anyway?) panel on the right side of the boiler. Is there an extra 'slot' on that panel ? i.e. room to wire another circulator ?

I was going to suggest the zoning approach that Xiph mentioned, but decided that since you will be moving out, you might not want to 'go there', but depending on how the house is laid out, and how you are able to split the loops, and if there IS an extra slot on the control panel, it might make sense to split the big loop into two separate pumped zones.

Why are you looking to go from 3/4" CU to 1" PEX ? If you do run 1" and split the loop that way, you should be removing as much of the 3/4" CU as you can. The 'short section' I was referring to was the takeoff nipple on the manifolds.

You may well be right about why they used 1/2" ...
 
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Old 07-23-08, 05:54 PM
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Why would you replace the 1/2" pex with 1" pex if the baseboard is 3/4" copper? Use 3/4" pex.
 
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Old 07-23-08, 07:58 PM
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Whoops. You're right NJ Trooper. That's what happens when I try to create the schematic from memory and cluttered photos. I busted out my calipers to make sure I had the piping sizes correct.

1) Both the cold water supply and the DHW are 1/2 cu

2) That return line shouldn't be marked 3/4 cu. The supply and return manifolds are both 1-1/2 cast iron

3) The SuperStor has 1" connections so they reduced it to 3/4" for the boiler connections. Maybe that's all he had in his truck that day.

4) There is an ARGO ARM861-3DP "Control with priority". The SuperStor is connected to the priority circuit and the heating loop is connected to the first thermostat/circulator circuit. There is one empty thermostat/circulator circuit.

All of the convectors are 3/4" cu so to repipe with 1" PEX, I'd have to have a way to connect it to the 3/4"

It looks like I'd be able to use that ARGO in place of the ZVC-403 in the plan xiphias posted.
 
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