hydronic circulating pump and TRVs

Crunch

I read a post by Dan last night regarding a potential problem with a circulating pump when installing TRV valves in a building.  Our situation follows.

We are a 27 apt co-op building in NYC.  Con Ed will subsidize the cost of TRV installation.  We are considering doing this on the south side of our building, roughly half the apartments.

For unknown reasons, each apartment on the south side of the building has one long pipe running throughout the apartment with 3, 4, or 5 radiators on it.  There are two old gate valves on the pipe, one at the riser at the beginning of the loop and one at the end at the return.  There is no ability to independently regulate heat at the radiators.

To install the TRVs, we'd also have to install a 2nd bare bypass 3/4 inch bypass pipe in each radiator (which we already have on the north side of the building), so that hot water will be able to bypass the radiator and go to the next one down the line.  We'd also replace all gate valves with new ball valves, and add a ball valve next to the TRV on existing finned tube in case it is ever needed.

Overall, the above might entail adding 40 to 50 TRV valves on the south side of the building, along with the associated bypass piping.

Questions:

1)  Since we would be adding bypass piping in each radiator in addition to the TRV valves, would we still have the same potential issue with the circulating pump?  The existing pump is a B&G 2-1/2 inch booster pump, "LD3 HD3 PR 2-1/2".

If we are adding the bypasses, seems like the pressure would not increase even if all the TRVs are closed.

2)  In a small building like this, how much value are the TRVs actually going to add vis-a-vis just turning a ball valve on or off?  I use ball valves on the north side, and it seems to work fine.  The only reason we would use TRVs is the Con Ed subsidy.

3)  Should we be putting a globe valve on the finned tube in lieu of a ball valve?

4)  Any other potential pressure problems that we should anticipate?

Thanks,

Crunch

Paul Pollets

TRV's and Pump

The TRV's will give very accurate setpoint control for each radiator. Much more accurate than a ball valve. A setting of "3" usually corresponds to a 68 degree room temperature. I'd replace the existing pump and use either a Grundfos Alpha or Magnum "smart" pump, which would be sized according to demand flow rate and head loss. The "Smart" pump may possibly eliminate the need for any bypass. Talk to Peter at www.heatlines.com if you need more info.

Henry

Spaghetti

This is a typical installation for condos and up scale apartments. Except, that you don't have any temperature regulation! Most of the ones here will have a either a motorized valve or (oh NO!) a pneumatic one. You can't install TRV on a spaghetti system ( you can but I have a patent on that)! This is a system that  runs room to room in series. The easiest way to control temperature in each condo is by installing a motorised valve on the supply side with a thermostat in the hallway. It only needs 24 Volts and a bit of wiring. Additionally, you should have some Outdoor Reset which will pay for itself in no time. We have done some of these types of energy projects with great payback!

Crunch

Will still need bypass, right?

Paul,

How would I get the TRVs to work without bypass pipes in each radiator?  Without bypass piping, if one TRV closes, the whole line of radiators in an apartment will go cold, right?  The pump shouldn't have anything to do with that.

Crunch

Paul Pollets

Piping

The TRV's need a supply and return to each radiator (or BB), or rather each BB should have its own S&R to the branch or main. I've seen where TRV's have been installed on a monoflo system, but tricky. Series piping won't work.

Mark Eatherton

Yes to the bypass requirement...

A company named Enerjee use to make a three way non electric TRV valve with bypass. I believe that they were actually purchasing them from Oventrop over in Europe, and I have seen them in their European catalog.



You will probably have to place a personal call to get the information needed.



http://www.oventrop-na.com/us/index.asp?sprache=US



Heres a picture of the Enerjee Valve from an 02 catalog



Good luck



ME.

kcopp

If he uses....

a Delta P circ he does not need the bypass..... Grundfos magna/ wilo stratos. Energy savings to boot!.

Crunch

Yes, Mark

Mark,

Yes, on a small scale, these pictures are exactly the type of bypass piping we'll need to make these TRVs work.

Any thoughts on the need to add a variable speed pump to mitigate any pressure build up at the TRVs if we're adding the bypass piping at the same time.  With the addition of the bypass piping I would think the pump will still see the same loop it used to see, even if all TRVs are closed.

Crunch.

Mark Eatherton

Correct...

Constant pressure/variable speed circulators only work on 2 way valves.



ME

Crunch

No new pump?

Mark,

You lost me there.  Does this mean we don't need a variable speed pump as per Dan's article on TRVs and pumps of a few months ago?

Crunch

Mark Eatherton

Not required...

The TRV's Dan was referring to are a throttling type of 2 port valve. If it closes off, flow stops in that branch circuit.



With the 3 way valve, flow is not decreased to the branch, only to the load, but the pump doesn't "see" that. The pump only sees the open hole in the system that it needs to fill, and consequently, it runs continuously on high speed.



There is an inherent reduction of energy required to move water with the ECM pump motors, but you wouldn't be taking advantage of the variable speed function. Only the wire to water efficiency function.



Can you give us a link to the article Dan wrote?



Thanks



ME

Mark Eatherton

Kevin...

It is base board in series. HAS to bypass, otherwise other convectors will starve.



ME

Crunch

Dan's Post

Thanks, Mark.  Got it.

The link to Dan's article is http://www.heatinghelp.com/article/183/Plumbing-Mechanical-articles/2383/Tales-of-TRVs-April-2012.  There is another very similar article out there of his with a slightly different twist, but not by much.

I'm a newbie to begin with, treasurer of our board actually, who didn't know a boiler from a broiler last fall, and Dan's comments about the pump when installing TRVs were not something I would have thought of at all.  BTW, he did confirm last night that the situation I described would not require a different pump since we will be adding the additional bypass circuits.

Crunch

Mark Eatherton

We knew that ;-)

I just wanted some more Holohan articles to read ;-)



Thanks for learning.



ME

gennady

VFD pump

Variable fd pump is a working very good with TRV and bypass. if bypass is smaller than line and/or balancing valve is installed on bypass, the 2 way TRV will work just fine. just set balancing valve to bypass extra flow, when fully open TRV delivers calculated GPM across radiator. also P/S has to be done and outdoor reset operation implemented.



Here is the link to danfoss explanations  http://na.heating.danfoss.com/PCMPDF/Series%20to%20parallel%20appl_VAGWA122.pdf

Mark Eatherton

Clarification please, Gennady.

You said :Variable fd pump is a working very good with TRV and bypass. if bypass is smaller than line and/or balancing valve is installed on bypass, the 2 way TRV will work just fine."



Do you mean that you have TRV's a VFD pump AND a bypass? If so, this goes against the recommendations when using a VFD. The VFD will always see a "hole" in the system that makes it stay in higher speeds, attempting to fill the hole.



Having a pressure activated bypass with a fixed speed pump is like driving your car with one foot on the brake, and the other foot on the accelerator. Your foot will only be off the brake for about 2 % (at design condition) of the time.



How is your system configured? Just curious.



ME

Zman

Delta T?

Would this be a good application for a delta t VFD with a moderate pump curve? It would respond to the temp drop cause by the valve opening.

Food for thought,

Carl

gennady

VFD pump

When setting up VFD pump, it is set to maintain pressure differential in the system. same as when differential pressure bypass with constant speed pump used. The only difference is in conventional setups pressure is maintained by pressure regulator, and in VFD setups it is maintained by RPM of the pump

Mark Eatherton

I misunderstood your post...

Wanted to make certain that other people reading it didn't do the same.



Thanks for the clarification.



ME

Crunch

Thanks for sharing

Mark,

It's been a huge learning experience, but I've enjoyed immensely, and my thanks to you and others for taking the time to share your knowledge and experience with newbies like me.  Sort of like a modern-day version of the guild system, I suppose, and I hope it fluorishes.

If I didn't have a full-time job and a need to make a living as a CPA, I'd spend a lot more time learning even more until we got our natural gas consumption down to an absolute minimum, and the wintertime comfort level of residents at an optimal point.  Can't tell you how much progress we've made in the last 12 months.

BTW, someone from Pennsylvania who goes by tk03 at www.comfort-calc.net was exceedingly generous with his time and expertise, and guided me every step of the way.  I literally couldn't have done it without him, and will be forever grateful.  Sometimes there were communications problems, but he never made me feel like I was asking a stupid question.  He patiently let me come back at him 2, 3, 4 times until I got it, at which point we moved on to the next issue. 

There is a thick, juicy steak or two at Gallaghers with his name on them, along with a couple of Broadway show tickets, if he ever gets into the Big Apple.  I doubt he'll take us up on the offer if he does get into the city, but he should.    

Mark, if you have any experience with EMS controls, I've posted another question on the controls forum.  Con Ed is pushing jazzed up EMS controls (they'll subsidize up to 70% of the cost), but I'm not sure how useful it would be for us, given the gains and tweaks we've already made with the existing Heat Timer box.  Any insights would be much appreciated. 

Crunch

Paul48

.

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Crunch

Oventrop 3 Way

Mark,

 

Couldn't find anything current on Enerjee, but did find Oventrop stuff.  Looks like the Oventrop three-way diverting valve "Tri-D" model is what we want, and it sounds like you've installed some of these.

 

Questions:

 

1)  Where did you get these?  I can't find them for sale anywhere on line.

 

2)  What was the cost roughly?

 

3)  Can they be operated manually without the actuator?

 

4)  Looks like the only type of actuator they can use is a remote unit, not a snap-on.  Is that correct?

 

5)  How's the performance?  Is there a smooth, graduated shift in flow from the finned tube to the bypass pipe, and vice versa?

 

6)  It's hard to believe, but the only other similar type of valve I could find was a Danfoss bypass valve, but that was only a 1/2 inch model.  Does that sound correct?

 

7)  Depending on cost, we may want to just install manual 3-way ball diverting valves.  How well do these things work?  It's not completely clear from the info on line, but it sounds like the flow modulating characteristics of two way ball valves have largely been overcome in many of the 3-way valves such that they give pretty good and even flow transition from one output to the other.  Does that sound right?

 

Thanks,

 

Crunch

Mark Eatherton

Answers...

Questions:



1) Where did you get these? I can't find them for sale anywhere on line.



It's been at least 10 years ago since I've used them. May not even be in business any more.



2) What was the cost roughly?

My memory isn't what it use to be, and we don't discuss pricing on this site.



3) Can they be operated manually without the actuator?

Most TRV's come with a shipping cap thread protector that can be used as a manually operated valve, but that kind of defeats the purpose of having the control head on the valve, and will end up creating situations that are too hot or too cold.



4) Looks like the only type of actuator they can use is a remote unit, not a snap-on. Is that correct? Have never used Oventrop's bypass valve, but all of their other valves take all of their operators, so I'd be surprised if it doesn't. Talk to the people at Oventrop NA.



5) How's the performance? Is there a smooth, graduated shift in flow from the finned tube to the bypass pipe, and vice versa? Yes. All non electric TRV's are a very slow acting valve, regardless of wether its pinching off flow or diverting it to another stream. Their operation is proportional to demand, not BANG BANG type of operation.



6) It's hard to believe, but the only other similar type of valve I could find was a Danfoss bypass valve, but that was only a 1/2 inch model. Does that sound correct?

It is not uncommon to have a control valve that is one pipe size smaller than the pipe it is connected to. Unfortunately, due to mis information, people install the same size of valve as the pipe its connected to, when in reality, in order to get exact control over the critical flows, it should have a smaller valve, creating more restriction to flow. Its called "valve authority". It's also a matter of checking the connected loads, and whether or not they are correct.



7) Depending on cost, we may want to just install manual 3-way ball diverting valves. How well do these things work? It's not completely clear from the info on line, but it sounds like the flow modulating characteristics of two way ball valves have largely been overcome in many of the 3-way valves such that they give pretty good and even flow transition from one output to the other. Does that sound right?



Again, having a manual diverting valve is only as good as the people tending them. No automatic control. As for transition, it has to be proportional. As you close one port, you are opening another port at the exact same proportion. A 2 way ball valve doesn't even begin to have any influence over the flow until it is at least 75% closed, hence they are not recommended as flow regulating device. Running them in a nearly closed position will also score the seat and ball, and then when you need to close off the valve, it will not shut off completely.



If comfort is your primary concern, and energy savings secondary the non electric TRV's are really a worthwhile investment. In situations like yours where everything is running wild, there is a huge energy reduction potential because people will quit using the double hung thermostat (window) to maintain comfort in their space. Once installed, a visual confirmation on a decently cold day will find all windows closed.



ME

Crunch

Oventrop vs. Honeywell

Mark,

  

Thanks.

 

I spoke with Oventrop US today and also got a quote from a contractor who wants to use a Honeywell vavle, V135A 1014.

 

What do you think?  I'm leaning toward Oventrop due, in part, to some of your previous comments on HH.com.

A few jpg attached.

 

Crunch

Crunch

Duplicate Cancellation

Crunch

JPGs clarification

The first two JPGs are of the Oventrop valve; the last is of the Honeywell valve.

 

Crunch

Mark Eatherton

Is this going to be installed on baseboard or radiators?

Because if it is going to be installed on baseboard it is going to be a tough retrofit. The operator normally has to be installed out the front cover, or the end cap of the baseboard. Otherwise, the sensing element will pick up the convective energy leaving the convector, and cause it to shut down early.



Personally, I don't usually endorse a product unless I've used it, and I've never personally used any Honeywell TRV's. Not to say they are good or bad, but I've never placed any in the field.



Look at the pattern of the Enerjee valve compared to what you are proposing, and I think you will see my point. If used on standing iron radiation, it could use a remote cap tube controller to get the sensing element away from the heat source. Even the Enerjee requires some special, odd ball fitting to make it work.



In a pinch, I have seen people use a regular 2 way, and pipe a balance cock into the bypass piping. Not perfect by any means, but a heck of a lot better than what you have going on right now.



ME

Crunch

Yup, a tight squeeze

Mark,

This will be on baseboard hyrdonic 3/4 inch pipe.  Don't know if it is Slant Fin or not, but similar dimensions, about 71/2 inches tall radiator housing from the floor.

 

You hit the nail on the head as regards the tight fit, but first an update on a couple of things:

 

1)  I did contact Oventrop USA in CT and will echo your comments posted elsewhere.  They were exceedingly helpful, pointed me in the right direction, sent me pdf and jpgs, and put me in touch with their manuf rep here in NYC.  The guy I was in touch with at Oventrop USA was an engineer and knew exactly what our situation was and gave me a complete parts list of what we would need to fix it, including parts for different actuator scenarios.

 

2)  For anyone wondering or hesitating, a call to Oventrop USA for help and guidance is highly recommended.   They want to help and won't make you feel stupid.  In my case, they wanted to consult with themselves internally and call me back with some specifics, and they did so an hour or two later.  I will go back to them with a final checklist of questions before we pull the trigger on this pilot project in the building.

  

3)  The first wholesaler the Rep recommended was a dud, but I called the Rep back this week and he gave me a new wholesaler.  Had a quote in an hour, and I swear it is at wholesale prices.  Honeywell's list on their website is about 7x's what I was quoted by the Oventrop wholesaler.  Amazing!

 

4)  I keep hearing from very different sources the same thing you said some years ago, Mark, regarding the high quality and reputation of Oventrop products, particularly in Europe.  Top shelf German stuff from what I gather.

 

5)  As to the making it retrofit issue:

 

a)  The whole thing, valve plus actuator head plus return bend or elbows, is going to be at least 9 inches.  Probably the actuator head is going to stick out above the radiator cover, which should be fine.  Given the way the flow will be, I can't see how we could practically pipe this horizontally coming out the end of the radiator.

 

b)  To get it positioned properly inside the radiator cover, looks like we'll have to use a lot of elbows to get eveything to twist and turn and then line up.  Any rule of thumb as to how many elbows to use on a hydronic system to minimize any pressure/flow problems, or is this a non-issue?  Can we use as many elbows or return bends as it takes to get the job done?

 

c)  A plumber was here today, and he was mulling the idea of moving the entire radiator assembly higher up on the wall so that some of the 9 inch valve stuff could protrude from down below.  I'm not crazy about that idea and would prefer to elbow things around in the existing radiator housing position to where they need to be if that won't create pressure/flow problems, and have some of the actuator assembly poke out from the top of the radiators cover.  What do you think?

 

d)  Both of the two actuator configurations for this particular valve use a remote sensor about 6 feet away.  Oventrop does offer a completely manual control directly on the valve, but apparently no thermostatic control directly on the valve body.  All automatic control seems to be via remote sensor at least 6 feet away.

 

Appreciate your thoughts on the elbow issue.  Would prefer to not have to deal with it, but I don't see any way of avoiding it.  Anything else/issues we are missing?

 

BTW, not particularly relevant to any of the above, but from what we could see today when the plumber was here, the original installation of the radiators on the southside of the building vs those on the northside must have been done by two different plumbers.  There were telltale signs regarding the way the piping twisted and turned that indicated that the two systems were installed by two very different plumbers, for unknown reasons at this point.

 

Thanks,

 

 

Crunch

Mark Eatherton

The less elbows, the better...

Each elbow has an equivalent length of 3 linear feet of pipe. The only way to know for sure if it is going to create issues is to perform the iterations required for pump sizing. That entails having to map out all individual circuits, taking into consideration every fitting, and anything (3 way diverter and fin tube) that will create resistance to flow. Once this is all done, the existing pumps performance curve can be compared to the theoretical pressure drops, and if the pumps curve is higher (within reason) than the demand curve, then you are good t go. Otherwise, you may need a larger pump. If the existing pump is WAY to big, then you will have to incorporate a pressure activated bypass to avoid other issues.



The only rule of thumb in this area is that engineers assume that for whatever the actual measured length is, that fittings will not exceed 50% of that length. I avoid rules of thumb because they generally result in significant over sizing of whatever they are applied to...



There are really no "industry" standards as it pertains to installing and piping baseboard, other than trying to put and keep the board below windows. Route manner and method is a matter of personal preference and experience.



ME

Crunch

Refinement

Mark,

 

Thanks for the insight.

 

As near as I can tell, we'd probably need 10 elbows to maneuver around to get the Oventrop valve positioned properly relative to the fixed postion of the existing plumbing and radiator housing.

 

In terms of pumps, we have two B&G 2-1/2 inch booster pumps plumbed in parallel.  For years, both were run 24/7 at the same time.  In the last 4 years, only one pump has been on.  No noticeable difference.

 

We replaced one pump and bearing housing completely last winter (NYC board president from CA and I, a CPA from upstate NY, did it ourselves, chuckle, chuckle), and tried running both pumps during a cold spell.  The pumps whined a bit more, but no one on the cold line of apartments in the buiding noticed a difference.  Two pumps vs one seemed to be a dud in terms of comfort in the building.

 

Without going through all the calculations, which I don't have enough data to do, I would guess we are adequately pumped, and we do have the capapcity to add an identical pump in parallel if need be.  I know when we were bleeding last year on the top floor, we were getting plenty of flow on the top floor once we replaced the pressure reducing valve and backflow preventer on the boiler.

 

So, maybe we'd be adding 40 elbows per apartment, or the equivalent of 120 feet of pipe, x 3 apartments in this pilot project for the equivalent of 360 extra feet of pipe for 3 overheated apartments.

 

What's your hunch?  Too many elbows for it to work?  Nutty? 

 

Another issue is this:  Danfoss recommends that the bypass pipe be at the top and back of the radiator, probably to minimize interference in the chimney effect air flow in the radiator.  However, the Oventrop valve is designed to have the bypass pipe run at the bottom of the radiator finned tube, tight against the finned tube, and probably blocking about half of the air flow coming up from underneath the finned tube.  At least in our building where the finned tube can't be more than an inch off the floor, and tight against the wall.

 

Issue:  run the bypass pipe tight underneath the finned tube with fewer elbows needed at the Oventrop valve, where space is tight, or run it at the top and back of the radiator, where space is less tight, but more elbows and finessing would be needed to get the bypass from the bottom of the valve up to the top of the radiator.  The 10 elbow estimate mentioned above assumes we direct that bypass pipe from the bottom of the radiator housing up to the top of the housing and behind the elbowed piping for the Oventrop valve.

 

Another option would be 3 way ball valves.  Not to be a PITA about it, but ran ito another website tonight, Parker Hannifin's, that indicates 3 way uncharacterized ball valves don't have particularly good flow characteristics.  When the two outlet ports are minimally opened, total flow from these settings is something like 40-50% of total flow for a fully open valve, which doesn't seem particularly good.  This is the 2nd time I've seem similar flow data, the first being some site for George Fischer valves.

 

And I'm not sure characterized valves are worth it, either in terms of the their pressure/flow characteristics, or in terms of their cost/degradation over time.

 

 

So I'm not sure how good an option 3 way uncharacerized ball valves would be either.  If we did a lot of that, I can almost hear the pump whining in the basement during mild weather.

 

Which way to go?  As I've said before, any form of real control would be better than what we have had for the last 20+ years.  Automatic control is mere icing on the cake, not the cake.

 

Crunch







 

Paul_34

trv

i was on a job today and it was a monoflo tee set up and somebody 25 years added 20 zones valves to the system and the building owners didnt know why some of the zones were cooler there others. 

Paul_34

"

I was at a job today and they have the same problem, some contractor added 20 zones to a monoflo tee system. and they don't know why some of the zones are cooler and there have been other contractors working on this system in the last 10 years, they still did catch it.

Mark Eatherton

How are you going to know where you're going if you don't know where you are right now...

And bear in mind that you've already had flow "issues". As long as you use the same number of els on EVERY branch, the negative effects will uniform. If all valves were open, and calling, and you had Gage's on either side of the pump, you could see exactly where the pump is currently operating on its performance curve. The B and G pumps typically have a flat curve characteristiic which is in your advantage. You didn't give enough of a model number tho. Go to xylems web site and find out which pump you actually have.



As for bypass pipe location, so long as it is in dead center alignment directly above the heating element, it doesn't matter wether it is above or below the element. It represents the same resistance to air flow.



Without Gage's before and aft the pumps, you are only guessing, and your guess is as good as mine. Pumps in parallel double (approx) the system flow. That indicates to me that your flow issues are not a GPM problem, but more of a PSI problem.



The problem with an uncharacterized 3 way ball valve is that it has to be 90% closed before it begins having any influence over the flow. In other words, you are trying to control 100%of the flow range with 10% of the valves throw. Tough to do. It ends up being an all or nothing operation, and not proportional, which IS a favorable condition.



You still haven't considered an earlier option of a 2way TRV with a manually adjusted bypass valve, which should be a lot easier to install. Only tricky part of that is the adjustment of the flow through the bypass with the TRV completely closed. You'd probably have to "hear" the bypassing flow. That or pop for two balancing valves per branch circuit that uses a pressure differential gage for adjustment. Even that would be a delicate balancing act.



ME

Crunch

21/2 inch

Mark,

 

Thanks.  The B&G pump is either a No. 2-1/2 or LD3 Booster pump.  They're essentially the same, and the link to that Xylem page is http://completewatersystems.com/product/series-ld3-hd3-pd/.  As I said, we used to have both pumps running 24/7 for years, but have been using just one pump in the last 4 years.  Replaced one pump this winter, turned them both on for a few days during a cold spell, no noticeable difference.

 

I hear you about gauges, but we have none.  Would also like to add a water usage gauge on our cold water fill, but haven't done it yet.  No leaks that I know of, but it would be nice to know.

 

Took some measurements yesterday:  finned tube is about 2 inches square, and 1-5/8 inches off the floor, as is the bottom edge of the front plate of the radiator.  The front plate is 4.5 inches tall.  Do you still think we can put that 3/4 inch pipe under the element without adversely affecting the chimney effect?

 

I would thnk so, but don't want to take a left turn and have to redo it, especially since Danfoss and Slantfin show a 2nd pipe at the top of the radiator box, and no mention of running one at the bottom.  It will certainly be easier to install at the bottom of the box and would use a few less elbows than if we had to finangle it around to be at the top of the box.  Oventrop did say we can mount the valve upside down, if that helps.  Cv for the Oventrop valve is 5.22.  Is that good?

 

I also toyed with the idea of just raising the element up an inch or so in the box, but it won't change the number of elbows used (just where they are located), and it might very well reduce the chimney effect by moving the element that much closer to the top of the chimney.  Not sure how that would play out.

 

FYI, as best I can tell, we are getting good pressure throughout the system now with the new pressure reducing valve, expansion tank, etc. etc.  It consistently varies between 30 and 40 pounds, and the top floor always has good flow once we've bled the air out.

 

But there is that one weird cool line that used to be hot.  A topic for another day!  And also for another day, we do have bypass piping in the radiators on the north side of the building, apparently added after the gut rehab in '80s. (the cool line is on the south side).  Probably 45% or so of the total radiation in the building.  But we only have a ball valve on the finned tube to control the flow, nothing at all like the Oventrop valve.  So when residents have the valve open for heat, the system is seeing those two big holes to fill, finned tube and bypass, when there should only be one. 

 

Yes, I found a graph yesterday on Tyco's site showing the total flow on an uncharacterized 3 way ball valve.  Not at all smooth/proportional, or continuous flow.  It was a U-shaped curve, with the lowest flow when both ports were partially open, and the highest flow when either of the ports was completely open and the other closed.

 

I've thought about a more expensive characterized valve, but, honestly the Oventrop vavle will probably work better if we can get it in there, and the price is hard to beat.  With actuators, the Belimo and Calleffi things I saw were pricey.

 

Board president and I have discussed some of the manual options, including a manual bypass, but we both have concerns that it wouldn't be operated properly by the residents.  Most people here have no mechanical inclinations at all, and we probably wouldn't feel too comfortable if there was any possibility that the finned tube shut down and the bypass was inadvertendly also shut off at the same time.  Or, if both things were open at the same time and presenting two big holes to the pump.   As a practical matter, anything manual is probably not going to work, unless it were a characterized 3 way ball valve.

 

Question:  If we install everything and determine that it is too much for one pump to handle, am I correct in thinking the problem will almost certainly disappear if we turn both parallel pumps on?  The effect of having two parallel pumps running has never been very clear to me.

  

Thanks,



Crunch

RobG

Piping

Could you cut down on the fittings for your bypass by using pex or PAP for the bypass pipe? Even if you came off the TRV on the one side and the tee on the other with a 90 or 45 degee ell and then swiched to pex  (just make sure that the pex is strapped so it doesen't rub against the fins of the basboard). Just a thought. Rob

Crunch

PEX

Rob,

 

Good question.  I'll have to check, but I almost think that NYC code won't allow Pex.  There are some weird requirements here, and that might be one of them.

 

Crunch

Crunch

Confirmed 2 1/2

Mark,

 

Just confirmed we have the Series 2 1/2 inch B&G pump.  It you type in Series 2 1/2 on State Supply's site, a good picture of what we have will come up with a big 4 bolt flange. 



 

Crunch 

Mark Eatherton

I'm thinking you have other "issues"....

If it use to work before, but doesn't now, something has changed. You need to find the change ( I.e. closed valve) and fix it.



If the pumps don't have check valves on their discharge, when running only one pump, the fluid is short cycling around them umps. You can run just one pump, but an isolation valve will need to be closed OFF on the off cycle pump.



Theoretically, running two pumps in parallel doubles the flow. Head pressure remains the same. If you did double the flow rate in the system, the pressure drop could be 3.3 times, which can cause problems by itself.



Without Gage's, you're simply guessing.



As for the baseboard, sounds like good old 500 btuh/lf baseboard, and I really don't think it matters whether the pipe is above or below the element, so long as the pipe is in dead center alignment with the heating element pipe, but would defer to the manufacturer. Most BBR has a carrier above the fins for mounting the return pipe, but I've seen it piped both ways, and it still worked. I think you're grasping for straws, and splitting hairs at this point.



The Cv rating is the pressure drop created by the device when flowing 1 GPM, rating is in PSI. The rating you were given is high, but typical. This is where the guess work has to stop and system design/engineering begins. You may need completely different pumps in order for the system to work.



Static fill pressure is dictated by system height. 1/2 PSI per vertical foot plus 5 PSI is the industry norm. Don't confuse static fill pressure with pump generated pressure differential. They are completely different, but interdependent.



ME

bob_46

Backards

Mark I think you got Cv backwards .I believe the number is the GPM with a one PSI pressure drop.

Mark Eatherton

You're right bob...

Thanks for the catch. Too many numbers rolling around in my noggin, and right now it's in bio mass conversion mode. Thinking about how to burn wood from the insides out in a controlled environment. Preliminary experimentation is quite impressive and holds some excellent potentials. Google "stump stove".



Got down to 41 degrees F here in Heeney last night:-) time to start thinking about using alternative energy to keep the homestead comfy.



ME

Crunch

check valve

Mark,

 

Thanks.

 

I assume you are referring to the pumps.  Both work now, but we only run one, and have only run one for about 4 years.  Prior to that, for at least a decade, two ran together 24/7.  Only reason for the change was a much more knowledgeable superintendent in the building who said we didn't have to run both at the same time and that they will eventually destroy each other if run at the same time.

 

There are no check valves on the pumps unless they are built in to the B&G volute but there are two big isolation gate valves on either side of each pump.  They do seem to work:  when open, you can hear the water running by the impeller, when shut, it is quiet.  Also, when we replaced the pump last winter, not much water slipped by the valves.  Maybe a bucket or two for the time we had the pump off the volute.

 

When both pumps were running last winter, we would slowly open the outlet isolation valve on the 2nd pump and bring that online.  Both pumps whine a bit when they're operating together, but I assume that is normal?

 

So, if the flow rate doubles and the pressure decreases, does that mean that running the two pumps together will not solve problems created by the installation of the Oventrop valve and bypass pipes?  Seems counterintuitive.

 

Why dead center alignment with the element pipe? Why not push it to the back of the box?  Agreed on the hair-splitting -- pretty much decided we'd run it underneath and see how it goes.

 

For what it is worth, the Cv on the Oventrop valve was a lot higher than the comparable Honeywell valve.

 



Crunch