Heating Help

Control Setup

@ July 30, 2010 11:30 AM in solar with radiant-control strategy

Rob,

How is your control set up to compare the temperature of the radiant return and the temperature at the top of the tank?  Do you use one controller with multiple relays?


Interested,

Martín Romero

Tubing Bends

@ July 8, 2010 12:34 AM in System Resistance Curve

Mark,

Thanks for the tip.  No wonder nothing turned up in my research with regard to pressure drop through the bends.

I'll continue to be mindful of the factors that you mention in your message.  No need to be wasteful.  I imagine that there are some regional scale factors that are used once the numbers have been run by the book.  I'll continue to snoop around.


Martín

System Resistance Curve

@ July 4, 2010 11:43 AM in System Resistance Curve

Forum Friends,

I'm working at understanding the system (resistance) curve for a Radiant Floor Heating System.  Clearly, fittings, valves, etc. add to the resistance of the flow in the system, but it seems that the actual radiant-floor loop is treated simply as length of pipe.  I've not seen it noted anywhere that the bends in the floor tubing increase the resistance.  I would think that a bend in the tubing would act something like an elbow.  Is my thinking off track in this matter?


Gracias,

Martín Romero

Drainback Combi-system Photos

@ July 3, 2010 11:31 AM in Drainback Combi-system Photos

Amigos,

For some time, I've been meaning to post some photos of my Drainback Comination System.  I'm grateful to this forum for all the design help I received while putting this system together.  The system has seemed to work well (based simply on amount of Propane used), but I'll need a few years to get some strong data.

There's nothing like putting a system together to gain experience.  Clearly, If I could do it all over again, I would research more and probably change a couple of things.

I welcome any questions and am eager to help if I can.


Martín Romero

Drainback System Specifics

@ January 9, 2010 11:33 AM in newbie drainback questions

Sunny,

Please give a few more specifics on your system, etc.: 

1. What type of panels and how many will you be using?
2. What part of the country are you in?
3. Will you be using a backup heating system?
4. How big of an area do you plan to heat?

Take note of previous posts discussing the use of pex in solar systems.


Peace,

Martín

New Controllers....

@ December 1, 2009 8:16 PM in Drainback - Unusual Behavior

are a must on my study list.  Thanks for all the information and support.  I'll keep up the study and work toward getting my system up and running again, implementing the ideas we've discussed.  I'll keep you posted

MR

Snap Switch/ lowest 'high limit' setting

@ November 28, 2009 2:08 PM in Drainback - Unusual Behavior

Solar friends and experts,

So what about a normally-closed snap switch that opens at 180 degrees or so and works on a 10-20 degree differential?  What would be wrong with this approach?

The radiant floor side of things (you're right, Mark, floor mass as storage) works on a normally- open snap switch that closes at 110 degrees and operates off of a separate controller.  I handle overheating in the summer by covering three of the collectors; the system worked fine all summer, and I don't consider the one hour to place or remove the covers too much of a burden.  I knew since the start that I would have to cover them, but it's only now that I REALLY understand why.

I'm also wondering if adjusting the controller high limit to the lowest (or a lower) setting could also help prevent some of the problems.

I'll have to read up more on data loggers and consider this as a system diagnostics tool.  I believe some of the new controllers already come with some data logging features.

15 gallon storage/Pressure valve

@ November 27, 2009 7:21 PM in Drainback - Unusual Behavior

I checked the drainback tank, and its pressure relief valve (no temp relief, it appears) is rated for 50psi. The tank holds 15 gallons; the collectors hold 5 gallons total when full, and the rest of the piping and components another couple of gallons. This gives about a 7 gallon or so cushion.  I run the system without pressure.

I'm not sure why the tank sprung a leak.  I'm pretty sure now that the pressure valve did not blow and that the water loss was through the tank leak.  I'm also sure that the high-limit setting on the Goldline-GL-30 DHW controller  was too high.  I had it set at around 140, but when all four collectors are on the DHW, the upper level temp (water side out of HX) can get way ahead of the lower level temp (water side inlet to HX), and by the time the sensor reads 140 degrees on the lower level, things might be boiling up top.  I don't really understand how that relates to pressure buildup yet, but I'm ready to learn.

Either way, I'll have to replace the tank.  I'll consider it part of my education, although I'm not solid yet on the tank leak.  It doesn't seem likely that it was due to pressure overload, since it does have the relief valve.  How likely is it that the valve is not working?

I'm grateful for all of your help.  This ongoing conversation has been a real gift.   I wish all of you a joyful and peaceful thanksgiving and upcoming holiday/Christmas season.


Martín

Drainback saga continues

@ November 25, 2009 8:39 PM in Drainback - Unusual Behavior

Solar Friends,

My education continues: after draining my system and removing the pump for inspection, I re-filled and re-fired - see the first entry in this thread.  The following day, I came home to a half-empty drainback tank.  The only thing I could figure was that a pressure buildup had occurred due to my failure to fully close the fill valve (my own invented physics), and the P&T valve had opened.  I re-filled, and there appeared to be a negligible water loss, but the system seemed to function OK. 

Today, I came back to the half-empty tank again (thanks be to the inspector for insisting on a drain pan), but this time I noticed that due to a programming error with my thermostats, there never was a call for space heat, so all four 4x10 collectors were feeding my 50 gallon DHW storage tank with external HX.  The temperature at the top of the tank was well over 200 degrees.  The drainback tank has a leak and a bulge, and I figure it was damaged by the high temperatures.  Any thoughts?

Too much pump

@ November 17, 2009 4:37 PM in Drainback - Unusual Behavior

Hot Rod,

I did the numbers manually, and the Taco 009 was right on the border with my system components and lift head (about 14 ft).  I think a 009 would have made it to get the lift, and once the siphon is established would certainly handle it.

I don't have the variable control, just the simple Goldline model.  However, I sure am getting a good education with all of this conversation and the recommended readings.  I'll know much more for the next system, and I'll consider some modifications to my present system when/if some dough becomes available.


Gracias,

Martín

Technical Documents

@ November 17, 2009 4:30 PM in Solar Hot Water Technical Documents

Fortunat,

Hot Rod also recommends this book.  I'm more determined than ever to get my hands on it, which I will soon.


Gracias,

Martín

Pulled pump cartridge

@ November 15, 2009 1:10 PM in Drainback - Unusual Behavior

Greetings,

I removed the pump cartridge and examined the impeller.  I'm no expert - it's my first time to do such a thing - but I saw no signs of damage.  I researched cavitation online and saw examples of damaged impellers, and mine doesn't look anything like those.

I'm now wondering howthe small particles were introduced into the closed loop (maybe some debris inside the piping came loose) and what the strange sound was at the valve/tee at the inlet of the drain back tank.

Please pass along any ideas or experiences that might be helpful.


Gracias,

Martín

Drainback Component Specs

@ November 15, 2009 10:34 AM in Drainback - Unusual Behavior

Hot Rod,

Yes: three-way zone valve just outside tank (caleffi). 

The SDHW HX is the quad-rod 36" from AAA Solar in Albuquerque:  http://www.aaasolar.com/ProdLit/Semco/QuadRodBrochure.pdf.  

The Radiant Floor HX is the Carlson 3.5 from W-cubed:  http://www.aaasolar.com/ProdLit/Carlson/CarlsonHESpecifications.pdf

The Circulator is Taco 0011.

I'm not sure if the tank is made to operate under pressure.  I looked at the tanks specs and it doesn't say; it does have a pressure relief valve, but something tells me I read something about the TPR being for system testing.  I'll have to look further.

I'm considering draining the system and looking at the pump cartridge.


Thanks for your help,

Martín

Drainback detail

@ November 15, 2009 8:58 AM in Drainback - Unusual Behavior

Hot Rod,

I forgot to answer your question: the drainback system is un-pressurized.


Martín

Drainback System Sketch

@ November 15, 2009 8:55 AM in Drainback - Unusual Behavior

Hot Rod and all others,

I've been in denial about a light crackling in my circulator since system startup.  Recent reading has me thinking that the tee 4 inches from the circulator inlet might be the culprit.  Otherwise, I believe I followed Lane's guidelines for circulator installation pretty closely.

I've attached a sketch.


Thanks,

Martín

Drainback - Unusual Behavior

@ November 14, 2009 9:25 PM in Drainback - Unusual Behavior

Greetings,

When my drainback combi-system kicked on today (SDHW portion), I noticed that the sound of the water returning to the drainback tank was unusual at the ball valve and tee right before the tank.  Normally, it just sounds like a muffled cascade into the tank, but today it had almost like a crackling or rattling sound at the mentioned valve/tee. 

Later in the evening, after the system had shut down and drained back, I looked at the sight tube of the tank and noticed that the water level was down about 1/4 inch from normal.  I also noticed some small brownish or reddish particles in the sight tube that I had never noticed before; usually the water in the tube is crystal clear.

Does this sound problematic to anyone?  If so, please drop a line.


Thanks,

Martín Romero

Technical Documents

@ November 7, 2009 8:11 PM in Solar Hot Water Technical Documents

Hot Rod,

Thanks for the leads.  I will follow up on these.  Thanks for your frequent and helpful contributions to this forum.


Martín

Solar Hot Water Technical Documents

@ November 6, 2009 10:31 PM in Solar Hot Water Technical Documents

Fellow Solar Enthusiasts,

I'm enjoying following the threads every couple of days.  I've written to the forum a few times and have derived great benefit, especially in installing my space-heating, SDHW combination system; it's taken me a year, but it's now in the fine tuning mode.

I'd like to learn a lot more about Solar Hot Water.  Can any of you point me in the direction of some in-depth technical/research documents that would help me gain a greater knowledge of this discipline.  I want to grow my skills and be able to contribute more fully to this "wall."  By the way, I've read the Tom Lane book several times over as well as the book by Rob Ramlow.


Gracias,

Martín Romero

high limit/low limit cycling

@ January 18, 2009 2:00 AM in High Limit/Low Limit recycling

Ron jr. I re-read this thread tonight, and I realized I had missed your question. You're right; about every couple of minutes, the burner will cycle. The temp increases to 200 degrees or so, then back down to just below the high limit where it kicks in again. My guess is that the thermostats are not calling for heat during some of this cycling, because the circulator is off. Thanks, Martin

High/Low cycling

@ January 11, 2009 12:08 PM in High Limit/Low Limit recycling

Chris, I'll have a look at this. Thanks for taking the time to help. Peace, Martin

High limit/Low limit cycling

@ January 10, 2009 11:02 AM in High Limit/Low Limit recycling

Ron Jr., Thanks for the reply. The hot water boiler is the 0090 Raypak Copper Fin. The aquastat is a honeywell and it has "l6008G 1009" on the top. I don't believe it's the thermostats that are causing the cycling, because the ciruclator often is not running during these cycles. Thanks, Martin

High Limit/Low Limit recycling

@ January 9, 2009 4:06 PM in High Limit/Low Limit recycling

Steamhead, If the boiler is wired to maintain heat all the time, does this mean that there is a low limit switch somewhere that is not tied to the thermostats? It sounds to me like such is the case, since the circulator is not coming on during those cycles. I don't know how to check for a stuck relay. Any suggestions? Thanks, Martín