Radiant boiler needed in Sunnyvale

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Old 12-02-10, 11:39 PM
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Radiant boiler needed in Sunnyvale

Up until Thanksgiving I was pretty happy with a Takagi TK2 driving our radiant slab.

Now, we generally have pretty good weather but it was in the mid 30's (which for the area is cold). Now generally we've been waking up to nice warm floors so the shock wasn't pleasant.

So, short story is the TK2 developed a hole in the vent area inside the unit and some corrosion occurred. The unit at least shut itself off. I think this was during the dawn of instant heaters for radiant floor and it should have had a condensate drain in the venting (but didn't). It's been patched but will need replacement. I've had a couple of different quotes.

Polaris Water Heater, Munchkin R2-T80M, Triangle Tube Solo 110.

I spent $5k 9 years ago, and you know, the old boiler was horrible in efficienty, but heck it kept on running. The current $6.5K (or so) quotes have me really wondering what I should do.

The Polaris looks simple enough to keep on chugging along while the Solo is like slim race horse.

I live in what is called an Eichler house. My house is horribly energy inefficient, but it's better than it was 9 yrs ago. 1700 sq feet, but it's shaped like a U with a glass walled atrium in the middle of the U and a wall of glass at the bottom of the U. No attic, but a 2x6 T&G ceiling with a foam roof. This spring we re-insulated the living room and one of the bedrooms upgrading the insulation and putting in a vapor barrier. All the 5 of the sliding doors are double pane and the floor to ceiling windows have a plexyglass insulating panel in the inside (which is suppose to be better than double pane but a pain in the butt to clean).

I plan on picking up a infrared thermometer to check out some temps.

I have considered doing the install myself (very handy) but then there is no warranty and heck the installers MUST know something to be charging so much.

Any other suggestions?

Thanks,
Mark
 
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Old 12-06-10, 10:59 PM
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Currently leaning toward the TT Solo 110, it's internals seem clean and the boiler looks bullet proof.

Mark
 
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Old 12-07-10, 04:34 PM
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If your home is as bad a heat loser as you make it out to be, then the TT 110 might be the right fit... but 1700 sq ft you should be able to get by with a much smaller boiler. As an example, let's say your house needed a horribly high 35 BTU per square foot to heat it... that's only 60K BTU...

I would definitely steer away from a water heater application. Move toward a real boiler, and between those two choices you gave, the TT would be mine. But do consider the size...

Please read this if you haven't already:

http://forum.doityourself.com/boiler...nt-boiler.html
 
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Old 12-08-10, 09:17 AM
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I've certainly been studying and reading up on boilers over the last week. A lot to digest.The difference between a Solo 60 and Solo 110 in heat output seems significant 47K vs 86K BTU. However, Sunnyvale certainly is generally a mild climate and the cold snaps are rarely that cold or for very long with 30 being about the worst we'll ever see here.

I can't seem to find the slantfin program that everyone has been using.

I've found an online one:
Home Heat Loss Calculator
and
weatherdatadepot.com

Shouldn't there be a way of plugging in the gas usage for say last year, the weatherdatadepot data for my area, the efficiency of the current 9 year old TK2 and get a reasonable estimate?

Mark
 
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Old 12-08-10, 09:50 AM
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Before you run off and purchase a new boiler, do you know why the Takagi corroded? I lived on one of those old Eichlers for a year (in Santa Clara, back in 1994) and I have heard stories about the copper (isn't it?) piping in those slabs corroding eventually. do you suspect that there might be some of this going on?

Also, could you describe how the heating system works? Is there one thermostat and six or so loops, or is it something more complicated? This might make a difference in how you supply the heat - if you don't have to worry about "small" rooms...

Jeff
 
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Old 12-08-10, 04:34 PM
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I did my heat loss using HVAC-Calc. It cost something like $50 for 3 months of use or something. I know the slant/fin is free, but I found the cost of the program I used not to be very significant in the scope of the project and was easy to use.
 
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Old 12-08-10, 05:15 PM
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There is a hole in the upper part of the TK2 where the vent gas is suppose to go into the stainless steel exhaust vent. This gas was then re-circulated by the fan for a while... (yeah, I should have taken the cover off at the start of the heating season and looked around). So the inside of the unit is not in good shape.

If I treat the TK2 unit as disposable, I could put a new one in every decade for about $1.5k (if I was to do the work myself). I'm leaning toward having a more substantial boiler at this point. Cold feet on Thanksgiving was not a welcome thing around our house. (Pretty much in the low 30's outside that day too!)

My copper radiant piping was checked last year (and patched). The previous leak was over a decade ago, so I think the copper piping is in ok shape. (Who can know for sure).

I'll check out HVAC-Calc, as you're right $50 is a drop in the bucket at this point.

There is an outside room with the boiler, it supplies heat to a manifold that is 2 rooms away in a closet that has 6 (or so) valves that I have never moved in 11 yrs. The house is on a slab that contains the copper radiant heat coils (spaced too far apart IMHO) and their is no attic with 2x6 t&g with a foam roof on top (thank god).

Mark
 

Last edited by mark_hoy; 12-08-10 at 05:19 PM. Reason: added rough piping layout
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Old 12-08-10, 05:55 PM
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Is your entire house one zone, with only one thermostat? If so, you might be able to get away with a mod-con boiler piped directly, without a system loop or a system pump, which would (in turn) save you a few $$$. I obviously don't know what you got a quote on, but for only $6500, you may already "have that discount."

I'd consider only two things if you decide to get a boiler: One, can the boiler be serviced locally, and two, how low will it modulate. I'm in Monterey, and the peninsula is a one-horse town, that horse being Heat Transfer products.

I have a Contender MC80 that modulates down to about 19,000 BTU, but my house is zoned so I alse have a buffer tank. If I recall, the TT110 only modulates down to about 30K, which is pretty high. I'd also second the advice to use a TT60 if you can get away with it.

Jeff
 
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Old 12-08-10, 06:12 PM
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Yep, the house is on one big zone with one thermostat. If I could figure out thermal lag and could couple the system with an external thermometer, boy would we be more comfortable...

Yeah, of course none of the 3 proposals have even suggested a heat loss calculation...
Awaiting bids from the other two with details. The one I have in hand has a Grundfos UP26-99FC pump.

Thanks
Mark
 
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Old 12-08-10, 07:37 PM
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Originally Posted by mark_hoy View Post
If I could figure out thermal lag and could couple the system with an external thermometer, boy would we be more comfortable...
That is known as outdoor reset and indoor feedback. In this case, you could get a little fancy and do one or more slab sensors, and one or more room sensors. Automatic sensing of slab, room, outdoor and system responds to match. The TT boiler in particular is good at integrating external controls. Surf around tekmarcontrols.com and see what presents.

The 26-99 is a honking big pump with a honking big electrical draw. Maybe you need that for all the piping, but maybe (probably) not. Ask them to show their work on flow rate, head loss, etc. that led to that conclusion.
 
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Old 12-08-10, 08:23 PM
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Currently there is a Taco 0011 and it's likely too big too. The piping is known to be restrictive, but heck, I'm willing to ask as one suggestion has been for a Taco 007.

Mark
 
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Old 12-08-10, 08:35 PM
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The outdoor reset sounds interesting, pity I have no way of easily running wires to my heating closet unless it could be multiplexed over the existing two thermostat wires.

Mark
 
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Old 12-08-10, 10:46 PM
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Mark,
If you'd like to see a Tekmar system in action - with a HT Products boiler in my case - I'm in Monterey and would be glad to show you around. It's a sophisticated system that I installed myself (except for the physical boiler) and it works great. I've got 7 zones - 2 large concrete floors, three wood floors, and 2 small concrete floored bathrooms. It's very, very sweet and very, very sophisticated, with floor sensors in each of the rooms and indoor air temperature feedback via the thermostats.
Also, regarding the pump, you might consider an Grundfos Alpha pump. The electrical draw is substantially less than anything else around, even if you don't need it's fancy features. Compared to a 007, it puts out roughly the same power in it's "middle" fixed speed mode and yet uses only between 20% and 40% of power - 15-30 watts instead of 80 watts.
Jeff
 
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Old 12-08-10, 11:37 PM
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jbaron: Thanks for the offer but I think I'll have to decline. While the computer engineer in me would absolutely love to fiddle around and create a wonderfully controllable system, my more pragmatic wife (and kids) would prefer a company standing behind what they have installed to come and fix things when/if it breaks. I will bring up the pump issues as a multi-speed pump sounds pretty nifty since it can 'auto-size'. I suspect if this was the spring, I would do this myself...

How do you guys determine the actual water flow through a system? With a system that is already in place built 50 yrs ago, it's really tough figuring out what the heck has been built. Amount of copper tubing (I guess I could measure the pipes at the manifold) per room, etc.

Thanks for all the help so far.
Mark
 
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Old 12-09-10, 10:34 AM
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I just downloaded the FloPro Designer by registering at Taco, see The FloPro Team is Taco-Hvac's professional development program

Wow nice program!

Mark
 
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Old 12-09-10, 10:37 AM
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Originally Posted by mark_hoy View Post
How do you guys determine the actual water flow through a system?
The flow rate typcially cannot be measured directly. The usual way is to combine the system head loss with the head-flow curve of the pump. The system head loss curve can be computed from the lengths and sizes of the various pipe segments - the procedure can be found by Googling.

Another approach is to measure the differential temperature across the boiler. Knowing that and the Btu/hr net rating of the boiler, you can compute the flow rate.
 
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Old 12-09-10, 05:22 PM
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Jeff: What do you think of your Munchkin Contender MC 80? It's been one of the suggestions but I'd dismissed it as it was lower efficiency, but given the turn down ratio of 5:1, it may actually be more efficient. It also seems to have a Vision 1 with outdoor reset option...

Mark
 

Last edited by mark_hoy; 12-09-10 at 05:37 PM.
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Old 12-09-10, 10:06 PM
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Heat loss is at least: 35k according to what I punched into FloPro designer. (Figured out how to do the roof material) but that's with a normal attic. I've also not taken account of the partially pitched roof over parts of the house.

So with 1700 sq. ft. it's about 20 btu/sq ft. Do these numbers seem reasonable for my area with a lot of floor to ceiling windows?

Mark
 

Last edited by mark_hoy; 12-09-10 at 10:38 PM. Reason: Fixed roof in FloPro
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Old 12-10-10, 06:31 PM
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Hi Mark,

Having been through the heat loss numbers on my house, yes, 20 BTU/sq. ft. sounds reasonable for this area.

What do I think of my Contender? What's there to think about? It works, it hasn't given me any problems, and it's quiet. Once I figured out how to get it to modulate (that took a while, first to figure out that it was not, and then to track down the right resources) it's way quiet, and produces very nice 84 degree water from 79 degree water. I really, really like the low turndown ratio, and I find that my Tekmar system is able to control the boiler very, very well, even with the fact that I have a buffer tank in my system. I do, though, still veyr much think that you need to by a boiler, more than anything else, that is in common use in this area. As I said - in Monterey it's either HT Products or an off brand.

I like Mike's idea of determining flow via the temperature differential through the boiler, and I myself have done this with my Contender. If nothing else, it's a very good learning exercise - I'm not kidding - do it and see what happens.

BTW, I don't think that you should consider efficiency until you know what the heeating system water temperature is going to be. If you are dead set on running a system with a fixed water temperature, say, 110 degrees or whatever, then your efficiency is going to be something like 92%, plus or minus. I think, having looked at efficiency numbers a tiny bit (but only a tiny bit) is that at the low end, the boilers are all the same. It's DHW - 160 degree or 180 degree water - where they differ, and that results in different AFUE (and other) efficiencies.

Jeff

PS. Did I say to try the GPM calculation? It's an easy experiement.
 
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Old 12-10-10, 08:02 PM
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Excellent news, my local plumbing shop likes the reliability of the Contender, so we're going with him. He'd like to use a Taco 007 pump with it in a direct loop.

Hmmm, having watched a number of the Taco online tutorials last night:

Now the thermometer gauge says 120 (which is in the water flow), so the TK2 could be maxing out and even modulating.

I'm hoping the delta on the pipes is reasonably accurate even if it's not absolutely correct.
Via my IrRed thermometer:
Supply = 96 degrees
Return = 78

GPM = (BTUH/DeltaT*500)
GPM = (188000/(96-78)*500) = 20.8 GPM (with a Taco 0011)

and given the Taco 0011 curves, I get a head of 12', so I think there is some error in my measurements or my thought processes since this seems low.

Mark
 
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Old 12-10-10, 09:23 PM
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188 kbtu/hr - is that the net boiler output, not input? In California? You must be a movie star in one of those big houses? ;>)

Why do you think 12' of head is too low? But, I think a Taco 007 would be somewhat puny if your stated heat output is anywhere near correct. You could tell him to reinstall your existing 011 and give you a credit for the 007 (same flange-to-flange dimensions). Or, tell him to install a new 011, and then you could retain the existing 011 as a spare.

As a point of reference: my boiler's net output is 125,000 Btu/hr, and I'm using a Taco 012 - quite a bit lower and flatter curve than your 011, but well above a 007. (I selected the the 012 because it closely matched the original B&G HV-series pump that had performed well for years - and I like the flat curve.)

I have used temp measurements from strap-on pipe themometers. I haven't checked to see how the IR measurements correlate. But of course, you're only looking at the differential.
 

Last edited by Mike Speed 30; 12-10-10 at 09:45 PM.
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Old 12-10-10, 10:50 PM
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I wish it was a big(ger) house. A Takagi TK2 primarily is a tankless water heater with 188K input and I think it was 85% efficient. How do I get an output number? Is it as simple as 188*.85 = 159K?

If so, then 20.8*.85 = 17.7 GPM and a head of 15'? (Which for a 1700 sq ft house with 4 bedrooms with 6 zones might be closer).

As to the actual measurement of the head, I have no idea. First time I've tried any of this, and suggestions more than welcome.

Mark
 
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Old 12-11-10, 08:46 AM
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Input multiplied by efficiency should give you a net number, or thereabouts. When you get the time, clock the gas meter and verify the input Btu/hr. When measuring the inlet and outlet temps with an IR meter, try to aim at a black pipe. When you checked the temps, were all the zones calling for heat?

The cat's meow for getting to the flow rate is to measure the pressure across the pump. I installed a couple of 3.5", 0-30 psi gauges. But it might be simpler, depending upon the arrangement of your system. The pressure at the expansion tank is constant, so you know that. And your boiler gauge, adjusted for the differential elevation, could be another data point.

At this point, I think you can go ahead and make a reasonable choice for the pump. With a 1700 sq ft house, a Taco 007 should typically be OK. Your seemingly enormous Btu input threw me off.

But with six zones, you want a pump with a relatively flat head-flow curve so that the flow in one zone isn't dramatically affected by the what the other zones are doing. Your 0011's curve is pretty steep, so I wouldn't use that. Either a 007 or an 0010 would be better. I would lean toward the 0010.
 
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Old 12-11-10, 09:29 AM
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I guess it would be more correct to say I have a single zone. I'm messing you guys up by using the wrong nomenclature.
The zones are each room and the zone valves are fixed in the back of a closet with no way of getting power/info from them back to the boiler room.

There is a variable 3 speed Taco 00R which is a 1/20 HP which would allow tuning. There is also the Grundfos Alpha which was mentioned earlier in the thread.

So many things to think about....

Mark
 

Last edited by mark_hoy; 12-11-10 at 09:39 AM. Reason: Forgot about the Alpha!
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Old 12-11-10, 09:29 AM
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When measuring the inlet and outlet temps with an IR meter, try to aim at a black pipe.
Always take measurements on identical material. You won't get accurate readings from copper pipe. Google "EMISSIVITY" for plenty of info on why IR thermometers are not to be strictly trusted. If you paint the spot you wish to measure with flat black paint you will get as close as you can to the temperature of the surface of the pipe. Remember that you are measuring the surface of the pipe, and it may not in all cases be the temp of the water inside the pipe.

You will get even more accurate readings of the actual temperature of the water INSIDE the pipe if you take a section of pipe insulation about 2' long and slip it over the pipe. Cut a round hole in the center of the section of insulation and center this hole over the flat black painted spot. Shoot the beam into the hole.

Know that you still may not get an accurate reading of the actual water temperature, but if you are measuring DIFFERENTIALS, and both measuring spots are ALIKE, you will get 'reasonably' accurate differentials...
 
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Old 12-11-10, 09:32 AM
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The cat's meow for getting to the flow rate is to measure the pressure across the pump. I installed a couple of 3.5", 0-30 psi gauges.
And you do need to apply the proper formula (which I've forgotten) to the readings in order to determine flow... Mike, do you have that formula handy?
 
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Old 12-11-10, 09:44 AM
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These formulas that get mentioned should be put into a sticky.
 
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Old 12-11-10, 09:47 AM
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Originally Posted by NJ Trooper View Post
If you paint the spot you wish to measure with flat black paint you will get as close as you can to the temperature of the surface of the pipe.
Found some black spray paint in my garage and put a spot on each pipe near where it goes into the concrete slab. It's not a perfect flat black, but at least each pipe will be similar and the delta is what I'm looking for.

Thanks,
Mark
 
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Old 12-11-10, 10:19 AM
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OK, this time I think I can believe the numbers as the temp is close to what the analog gauge says. In addition, the laser doesn't actually point to the right place when up close to the target.

Suppy=117
Return=76

So GPM = 85% * 188000 BTU)/((117-76)*500) = 7.79 gpm
Which is 25' of head on the Taco 0011 curves.

Mark
 
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Old 12-11-10, 10:33 AM
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Mark, I'm too lazy to read way back in the thread... my bad... but that's an awfully high flow for 3/4" pipe... which should be limited to something like 4 GPM. If it's 1" pipe, s'ok. Or if that's a total flow that's branching into several smaller pipes, probably OK too.
 
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Old 12-11-10, 10:51 AM
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Originally Posted by NJ Trooper View Post
Mark, I'm too lazy to read way back in the thread... my bad... but that's an awfully high flow for 3/4" pipe... which should be limited to something like 4 GPM. If it's 1" pipe, s'ok. Or if that's a total flow that's branching into several smaller pipes, probably OK too.
I agree, the winning bid on doing my new boiler has pointed out that the Taco 0011 is likely way too big and too high of water flow isn't good for the piping, etc.

If you guys have any suggestions of what gauges to install during the boiler work, chime in now! Remember, you are spending my $$.

As to the GPM calculations I've been doing, I think I've forgotten to take into account that the TK2 is programmed to output 120 water and that it's not likely using 188K BTU to do this and it's modulating down.

BTW: the Supply is 1 1/8" OD with the return being 3/4" OD

Thanks everyone
Mark
 
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Old 12-11-10, 12:04 PM
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OK, I'm still a bit confused. You only have one thermostat in the house, right? If so, then everything is on one zone. I would then just go along with the Taco 007 and be done with it - and forget all the esoteric flow calcs.

All of the Btu/hr numbers that you've listed so far, except the lowest, your heat-loss calculation of 35K, seem very high to me for a 1700 sq ft house in Sunnyvale - or even one in northern Illinois. I worked on a little project in Santa Clara, next door to you - and my recollection is that it doesn't even get below freezing there. But whatever - I'm generally ignorant about things in California.
 
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Old 12-11-10, 12:09 PM
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Originally Posted by mark_hoy View Post
BTW: the Supply is 1 1/8" OD with the return being 3/4" OD.
Standard pipe sizes are based on i.d. not o.d. The nominal pipe sizes would depend upon whether your pipe is steel or copper. But, at this point, I don't think it makes much difference - it is what it is.
 
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Old 12-11-10, 12:23 PM
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Originally Posted by Mike Speed 30 View Post
OK, I'm still a bit confused. You only have one thermostat in the house, right? If so, then everything is on one zone. I would then just go along with the Taco 007 and be done with it - and forget all the esoteric flow calcs.
Sounds good to me. While it's an interesting exercise, I doubt any of the numbers are really reliable enough to make any realistic choices. I was just trying to figure out what size of pump. The experience of my installer will be my guide.

Originally Posted by Mike Speed 30 View Post
All of the Btu/hr numbers that you've listed so far, except the lowest, your heat-loss calculation of 35K, seem very high to me for a 1700 sq ft house in Sunnyvale - or even one in northern Illinois. I worked on a little project in Santa Clara, next door to you - and my recollection is that it doesn't even get below freezing there. But whatever - I'm generally ignorant about things in California.
It's the first time I've used the heat-loss program and I think it's the 80 linear feet of floor to ceiling windows that are killing the numbers. Only in the 1960 with low energy prices and with a mild climate would anyone build one of these houses.

You are also right about the mild winter, while it does get into freezing, it's just for a couple of day for the entire winter and we consider it a very cold day for the area.

Mark
 
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Old 12-11-10, 01:29 PM
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Originally Posted by NJ Trooper View Post
And you do need to apply the proper formula (which I've forgotten) to the readings in order to determine flow... Mike, do you have that formula handy?
What I was visualizing (before this whole thread blew up and became somewhat moot) was this: If you can measure the differential pressure across the pump, then use the head-flow curve of the pump. Knowing the head, the pump curve will give you the flow rate.

The gauges on either side of the pump might need to be adjusted for elevation differences. And if either of the gauges is very far upstream or downstream of the pump, might need to horseback the estimated resistance drop in between the pump and the gauge. I've got 3.5", 0-30psi gauges on either side of my pump - close enough for government work. My 0-30psi gauges' dials are in 1-psi increments - easy to read within about 1/4psi.

If the expansion tank is connected close to the pump's suction, that pressure is known and is constant. In that case, you can get by with just one gauge - at the pump's discharge.
 
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Old 12-11-10, 06:41 PM
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Highly unlikely you're flowing anywhere near 8 gpm. And it would be bad if you were, AND seeing a 20-40F temp drop too.

A Wilo ECO or Grundfos Alpha would likely fit the bill and be a significantly smaller drain on your CA electric bill. Or as fallbacks a Taco 00R or Grundfos 15-58.
 
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Old 12-14-10, 07:45 PM
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I got in the TKRE02 Remote TK2 diagnostic panel today. It shows a 3.9 Gpm flow rate with the Taco 0011 pump. I have not bothered to find the head loss in the TK2 as it's coming out this week. (I'll be giving the remote to a friend who also has a couple of these units).

It also shows input temp, output temp and allows for finer temp adjustment than the dip switches.

Mark
 
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Old 12-18-10, 11:07 AM
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Just an update to close off this thread.

First off, thanks to everyone for the advice and ideas. This is a warm and welcoming forum that I feel has helped me understand my radiant heating system.

The new Contender MC80 is in with an outdoor reset temp. Comfy heat again! The amount of condensate created over night was more than I had expected, the cool exhaust output via the PVC piping is amazing. I have to double check if the condensate drain field has any marble chips in it as I would prefer to neutralize it's pH.

I went with an inexpensive Taco 007 pump (with ball valves for easy replacement) and pressure gauges on each side of the pump. I figure I can upgrade the pump easily enough if I need/want to and left the Grundfos Alpha for another time.

The old Takagi TK2 was very corroded in the heat exchanger! At a minimum a condensate drain should have been installed with the old TK2 system. The installation was double wall stainless steel all the way to the old cap which was made of sturdy stuff, but not stainless steel and it was slowly rusting away. The TK2 did heat my place for the last 9 years, but as a radiant heater, I think it is lacking.

Thanks again,
Mark
 
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