Heating Help

TAKAGI TK jr

@ February 18, 2010 12:19 PM in Which heater to use

I put one in my shop this fall, and wouldn't do it again.  the head loss thru the heater with antifreeze is too much for most circulators.  I had to run a 2699 on both the secondary loop for the heater and the primary loop into the floor to get enough fluid flow.

after much much digging I was able to come up with 20' head loss thru the heater.
I'm selling it to someone who'll be able to use it for DHW where it belongs.

karl

simple

@ February 12, 2010 11:35 AM in John Siegenthaler's simplified Combisystem for new construction

I don't see a single tank ever really offering the sort of performance we'd want from the solar at panel radiator temps.  I'm sticking to the radiant area that walls, floors and ceilings offer.   that is unless someone wants to make a 12' tall tank for good stratification

how about the best of both worlds: 2 tanks, one a HTP Phoenix or similar, and the other a TT Smart 120.  that tank has 120G of domestic in the center tank, and then 43 gallons in the shell.  an additional small DB tank on top would allow for pressurized DB operation, the boiler ports would allow it to interface with the heating system, and a FPHE off the side of the Phoenix would allow it to bump up the heating water to the ODR required water temps.  and it'd give you 160 G of storage in the solar tank.

this could all be done (if you set the DB tank above a 55G phoenix (at 55" tall), in a footprint of about 3x6' including access.  if you're set on storing heat in water, there's no way to get around the fact that you're going to need some footprint. 
maybe you could use a TTE boiler with 14G inside DHW storage.  That'd reduce the footprint some and would cover the DHW load as well.

or AIC makes a 120 gallon indirect instantaneous water heater.  120G boiler/solar water and 2? gallon DHW with 72 SF heat transfer area.  instantaneously heat your DHW to whatever the solar fluid temp is, and then bump it up with whatever you like, pressurized heating system, the top 6" of tank would allow you a drainack resevoir without sacraficing HX area.

someone let me know if you want to try these out, and I'll consult for free.

Thoughts?

Karl

one tank

@ February 10, 2010 11:59 AM in 2 tank systems Vs. One tank system SDHW

For systems that are a light combi system, I like to go with a one tank.  there is a bigger tank to absorb heat in the non heating season, and therefore close to 0 backup energy used for the water heating. 
In new construction where the hot water loads are conservative, I'd be OK with a single tank system.  if someone wants to fill a 100 gal tub anytime, use a real backup water heater.  my wife and I get by with an 80 gallon single tank system with electric backup (no choice due to utility room constraints)  if it's been cloudy for a few days, we have to be careful to give the element time to catch up between showers.  ususally not a problem, except when I have to take a shower right after her, getting ready to go somewhere.

we turn the element off from april to october usually, only turn it on if it's cloudy for a week. 

in short it all depends.   in wisconsin we're "strongly encouraged" to do a double tank system.

dawn solar

@ February 8, 2010 11:24 AM in Dawn of a new age???

There are good applications of Dawn solar in some cases.
we worked on a Dawn solar installation using sunslates, and it's OK.  I can't say much more than that. still too new to know more.
the primary use of the Dawn Solar in a lot of these dual system PV/ ST systems is to remove heat from the PV module, increasing it's efficiency. it's a semi conductor and is more efficient at low temps.

this is also A dawn solar/GSHP integration.  I still need to finish the integration work on it to make everything work smoothly, pre heating the incoming ground loop temps.  we're also going to use the dawn solar to do snowmelt on the PV system.

FYI, for flatplate collectors, if you integrate it with A GSHP system, and put your usable heat production temps in the 40-60F range, your heat output of the collectors doubles.  yep.  doubles.  that's in comparison to a usable range of 80-120 F we usually use for Flatplate collector space heating systems.

peace,
Karl

it's all system thinking

@ February 3, 2010 9:28 AM in John Siegenthaler's simplified Combisystem for new construction

Radiant system design (especially solar-integrated) rewards system thinking.  In order to think clearly thru the system, you need to have a thorough understanding of the limitations and strengths of each particular technology.
  for example:  I do really well with solar.  but I don't know geo.  so I have the ear of an experienced Geo contractor.  he keeps me in check on the reality of geo systems.  fortunately we both have similar needs for heat distribution (IE low delivery temps) so we're on the same page for heat delivery.
That said, when we have to integrate solar into a less than ideal delivery system, we will dump the heat into the space (say thru the retrofitted staple up tubes, because we're not going to redo the whole system) and with some fiddling around we can get heat into the house (which is the name of the game) between heat calls.  we won't meet design conditions, but we can extend the time between heat calls and use the existing delivery system.  it's just some controls. (one of my weak points, since I don't have a strong conventional heating background)
I start with the heat delivery of the collectors at my target solar loop operating temp, and then figgure out how much emitter I need to use to get rid of the heat once the DHW tank is satisfied.  unless I'm sending it to a large tank, which simplifies things since I then have a large buffer.

I will be doing a lot of the planning and design for the Midwest Renewable Energy Association's 400 level Solar Thermal Design Course, and will be asking around for information, mostly on heating topics.  Hopefully some here will be willing to share more of what they know, especially on my weak points. I'll probably start a new thread for that one.

thanks
karl

DB controls

@ January 26, 2010 9:45 AM in Tekmar / caleffi controls for DB

I'll either be using a single Taco 1400-45 or equivalent, or 4 taco
009's (one for each array), in which case I'll most likely be using a
single VS control for each circ. 

the VS controls will run a
009 right? I like the redundancy, and the fact that i can pick up a 009
anywhere, today. I'll be pumping secondarys to the 2 pools.

I'll leave the specifics of the controls out of the bid till we see what the new stuff is.

thanks
Karl

HTP COIL

@ January 26, 2010 8:35 AM in Heat transfer rates thru indirect coils

actually 20,000 btu would be fine for the types of applications I am using this top coil for.

the big question is what delta T the coil wall is under.  I'd be OK with a 20 deg delta T. 
I'm disabling the coil when the tank top temp drops below 110.  we're just dumping a little heat into the floor from there.

thanks
Karl

Tekmar / caleffi controls for DB

@ January 25, 2010 8:22 PM in Tekmar / caleffi controls for DB

Has anyone out here used Tekmar's solar controls?  specifically the 155, 156, 157?

I'm going to be installing a large drainback system, and want to do Variable speed circulator for both the primary solar circulator as well as the 2 secondaries that will be sending the heat to the 2 tube and shell HX's for the 2 pools.

Has anyone used the tekmar 157 for variable speed pumping a drainback system?

I'm considering using the Caleffi DB4, but need to run a larger pump than it's relay is rated for.
Hot Rod-- can you give me a hand on spec'ing caleffi controls for this? BTU monitoring as well as control of the solar loop?  

thanks
Karl

Transfer rates.

@ January 23, 2010 10:27 PM in Heat transfer rates thru indirect coils

you got it Bobby G

I have built a couple of systems that way.  I send the solar fluid thru the bottom larger coil, havepre-heated water in the tank, and if the tank is hot enough, and the space is calling for heat, I run the floor fluid thru the top coil.  I have a little buffer between the solar and my heat delivery system. 

I've only done this with really small systems like some tubes under a bathroom floor, under 100 SF.  

it works fine.  What I'm looking for is at what point will it not work satisfactorily.  that's where actual engineering comes in. 

WOW.   30-40Kbtu is a small zone?  I forget that you guys are all big time heating guys.  the houses we tend to work on have loads less than 40KBTU in central wisconsin.
my house in the design stage right now has a load of 22Kbtu for 1600 SF, and that is the topic of my next post.

Keep the info coming.

thanks,
karl

Heat transfer rates thru indirect coils

@ January 21, 2010 12:44 PM in Heat transfer rates thru indirect coils

Has anyone out there any curves or charts that can assist me in calculating the heat transfer thru an indirect tank's HX? 

I'd like to figure out how many BTUS i can reasonably get thru the top coil in a HTP superstore contender 119 SB, with say a 10-15 deg delta T from one side of the coil to the other.

thoughts? Rules of thumb I haven't heard?

thanks
Karl

John Siegenthaler's simplified Combisystem for new construction

@ January 19, 2010 9:34 AM in John Siegenthaler's simplified Combisystem for new construction

I've been  modeling the proposed system with the sorts of temps that a radiator system would need (with no direct DHW preheat)

say minimum production temp at 100F,
required temp of 145 deg,
with 160 SF of collectors with the same y intercept and slope as the spec'd panels,
no Heat exchanger, and 120 Gal storage,
the heat delivery from that array (in Wausau Wi, my design conditions) is 4.9 MMBTU

the same array with an 80% eff HX, 300 gallon storage, 120 deg delivery temp and 80 degree minimum delivery temp, in Wausau wi.  heat delivery works out to be 10.6 MMBTU.

Same load, lower delivery temperatures, even with the heat exchanger losses doubles the heat output of the array.  

Retscreen has been used to calculate the heat output of the array,  Monthly loads determined by my own calculator. 

there's probably some happy medium, price vs performance, as the second option needs an additional heat source, an addtiional DHW source etc.  and therefore more boiler room area, and more knowlegable installation personnel, and more costs.

Karl

thanks for clarification

@ January 16, 2010 9:22 PM in newbie drainback questions

thanks,
Yep.  I guess most of my concerns have been addressed.  I was definitely trying to figure out how to make this work with a polaris, aosmith, phoenix, voyager or any of the other modcon water heaters out there.

how 'bout moving the boiler components up on the tank, and make the return from collector dip tube return to the middle of the tank.  it ought  to significantly improve the solar performance.

my concern is that the entire tank will usually be over 120 degrees, and the solar performance will be severely degraded because of that.  it's all in the performance slope, and the performance in the SRCC cat D rating is the heating zone  (category D is temp inlet is 90F above ambient, with tested flow rate) 30 degrees out, 120 degree fluid temp is pretty standard winter operating temps, and I hate to get it much higher.

I regularly run a secondary loop off my solar primary line to feed solar heat to a fan convector or furnace coil.  one HX to DHW preheat, and no HX between space heating and solar fluid.

So many ways to move that heat around and so little time.

thanks again
Karl

simplified

@ January 15, 2010 8:41 PM in John Siegenthaler's simplified Combisystem for new construction

Yep.  It's a packaged system, but unfortunately. like most "one size fits all" systems it's not really ideal for any particular option.
It'd be substantially better if combined with infloor with delivery temps below 100F
but then it'd not provide adequate service to the hot water end load.
I think it's got potential, but I think I'd rather have it staged thru 2 tanks.  both to allow a little more storage, and provide real stratification.

I'll think on my piping scenario. probably based on a HTP phoenix or solar phoenix. I'm all about using off the shelf components. unfortunately my drawings won't be nearly as nice

well, if his intention was to get people thinking, I certainly am.

BTW, I'm getting ready to build a 1600 sf superinsulated house here in central wi.  Unfortunately, I'm going to be limited by the location of my collectors (roughly 100 feet away, slightly downhill.) otherwise I'd be all about trying this out on myself.

cheers, Keep pumping away.

karl

glycol in drainback

@ January 15, 2010 9:54 AM in newbie drainback questions

Plumbers always know best, right?
seriously, though.  the AF is cheap insurance in the frigid north.  water is allowed in specific cases, in the southern part of the state.  I sleep a lot better with antifreeze in my systems.

The requirement is actually from our rebate agency.  if you want funding, they want to make sure the system isn't going to suffer from a catastrophic failure a couple years down the line.  $10,000 worth of scrap copper on a roof, if the installer isn't around any more is no good.

If I recall,water heaters are usually sized by highest use, not "oh, they'll probably never use that much water at once"
 not too many customers are going to foot the bill for a large solar heating system plus hydronic heating system, and then be told they can only take one shower at a time.
I certainly wouldn't.
now, he does show the system using panel radiators, so we cold expect the tank temp to need to be 140F or so, which would reduce the HX size for the DHW heating, but would seriously reduce the heat output of a typical flatplate collector.  and having to do an evacuated tube system eliminates the drainback option, as discussed above.
add to that minimal storage.   If this is just a couple of collectors designed to handle the dhw load in the summer, and help standby losses, it worries me a lot less.

again, just a few musings from a solar thermal installer/instructor/designer. 
Should we move this to a new thread and invite siggy to join in?   I don't want to piss anyone off, but I feel strongly that drawings that are out there should be really well thought out, because someone's going to take it as gospel that anything designed by an engineer is going to be great, when it's all in the details.

cheers,
karl

blower speed adjustment

@ January 14, 2010 6:40 PM in blower speed adjustment

OK, WIll do.

I'll call the installer who put in the furnace.  I would assume they'd know how to do this if I can't figger it out?

thanks
karl

Siggy's schematic

@ January 14, 2010 2:14 PM in newbie drainback questions

Maybe I need some explanation on this one,
but I don't like a bunch of things with Siggy's schermatic. 

first: the solar hot in should be near the middle of the tank. avoid tank mixing.

second: where is the tank sensor for the DB pump? location is going to be critical in this sort of single tank system.  tank sensor for burner operation?

third: how big a HX are you going to need to heat 5 gpm from 45 F to 120 F with say 125 deg water (keeping temps down so the solar will actually do something.)
I come up with about 35 SF area for a FPHE.  single wall mind you.  like a 5x12x75 plate.

unless you're going to pay for another water heater?  ouch.

also what about the air in the system getting absorbed into the fluid.  there's a lot of water.  isn't this why we moved away from the compression tank, and amtrol made the air control valve?

is he proposing putting this together? and actually monitoring the heat output of the solar to the heating system?   I'd love to see how it runs.

karl

drainback evac tubes

@ January 14, 2010 1:44 PM in newbie drainback questions

Thermomax has their propriatary internal heat regulator that shuts off the evaporation/condensation cycle in the heat pipe.
I think it's maxed out at 110C.  but don't quote me on that.
I don't know that they are recommended for drainback, but I seem to remember reading that. 
I don't do any work with evacuated tube systems.  durability and snow shedding and all that.

I pressurize my drainbacks, if only to eliminate the possibilty of cavitation and steam popping.

I suffer thru a single heat exchanger between the solar fluid and tank, mostly because here in WI, we are required to use 30%antifreeze in DB systems, and the price of antifreeze.

karl

we'll answer your questions

@ January 13, 2010 10:07 AM in newbie drainback questions

That doesn't mean we'll tell you what you want to hear.  that's part of being a professional.

first: you shouldn't be planning on doing a drainback system for evacuated tubes.  most evacuated tube sytems are designed to have fluid flow thru them whenever there's sun. 
only one manufacturer I Know of will allow it.   the temps they can reach can damage themselves if left dry in the sun (like summer)

Especially with the evacuated tubes, you shouldn't use any PEX in the solar loop.  I have done it, but only in high mass systems, where there's 100 feet of copper between the collector and pex. (soaks up the high temp spikes with 50 lbs of copper)

Coils in the tanks should be copper.  Pex I think could be used in situations where you're pre-heating DHW, because the storage capacity of 300' of 3/4 pex would help offset the low heat transfer efficiency. 

I wouldn't do un pressurized heating loops unless I had a single loop (say to a fan coil or single raidiator)  or you were servicing each loop with it's own ciruclator.  then you should use stainless or bronze circulators if you want them to last more than a few years (there will be some oxygen getting in the water in a non-pressurized system. 

oh yeah, you'll also want to put a big wye strainer before the pump intake, with a clean out shut off.

all of a sudden, a couple of coils of 3/4 copper to pick up the heat from the tank doesn't seem too bad (use 60' of 3/4 type L soft to keep the surface area up, and head loss down)

reliability is key.  and closed loop pressurized systems have proven it.  but it's your house, so do whatever you want.
post your schematic and I'll post mine.

karl

blower speed adjustment

@ January 13, 2010 9:46 AM in blower speed adjustment

yep, I have the O&M for the furnace. 
I have no experience with the variable speed controls for furnace blowers. 
For internconecting these systems before all I have had to do is use an aquastat on the pipe heading from the solar piping to the hot water coil in the return. 

The aquastat closes at say 120 and opens at 100F, and essentially just parallels the fan switch in the thermostat, thru a second thermostat set to 75 F (high limit) in the house.  pipe gets hot, fan turns on.  no direct connection from the solar controls to the furnace controls. 

that's what I've done here, but the "fan only" setting the fan is running really slow, and not removing enough heat from the solar loop to keep the temp down and get the heat into the house.
According to the manual, It seems that dip switch 1 and 2 on  switch set 2 should change the fan only speed. 

I'll keep reading, and will welcome any advice.
Bugger that the system is nearly an hour away, kind of  a pain to go fiddle with and not know the answer when I go to the site. 

thanks,
karl

furnace model

@ January 12, 2010 1:26 PM in blower speed adjustment

the furnace is a > T9MPV125L20A1

variable speed blower, 90+eff. 125Kbtu.
the owner switched the dip switches on set 2, but it resulted in the blower not running at all.  yes, he closed the compartment to take care of the lockout switch.

suggestions?

thanks
Karl

blower speed adjustment

@ January 7, 2010 11:50 PM in blower speed adjustment

Hi All,
I'm trying to adjust the blower speed for the fan setting on a early 2000's tempstar furnace.  It has a 2 stage blower and 3? speed fan.  (super low on fan setting, low and high in heating mode)

can any one assist me in upping the blower speed in the fan setting?

Please help a wethead who's trying to understand furnaces.
This is for a solar heating integration.

thanks
Karl

Solar Standards

@ December 10, 2009 8:28 PM in Solar Code: Minimum standards guideline.

The Focus On Energy Standards are what has come out of 30 years of a real solar thermal industry in Wisconsin.  Not that there haven't been ups and downs, or black eyes.  But I can say that the standards on that application are more than enough to keep crap mostly off the market.  and as someone who has to clean up behind electricians, plumbers, and yes, sometimes mechanical contractors' solar installations, The dedicated solar thermal installer has a place in the inter-disciplinary world that overlaps the worlds of the plumber, electrician and pipe fitter.  Just remember that we have to uphold the highest standards of all of those trades in our own context.  at the same time.

My solar thermal system kept my house from freezing today at -3F when my furnace quit.  I got it started again, but it was almost the excuse I needed to rip it out and go radiant.

cheers,
Karl  (full time solar thermal designer and installer)