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Cadet Combi boiler

hot rodhot rod Member Posts: 7,011
I like the concept of a simple dual purpose boiler DHW producer. The Cadet uses a plate HX with a dedicated pump to provide instantanous DHW. The pump provides great flow and excellent DHW production, no pressure drop that you might expect with a 3 way diverting valve and a single pump.

Being empty nesters our DHW needs are low. With both the dishwasher and wash machine being equipped with timers we can space out the DHW loads, so only 1 draw at a time.

For a simple one temperature system, like mine this is an ideal boiler. A basic control does offer the ODR. It has a great sound deadening jacket.

The ThermoCon tanks buffers the 3 small loads, the low load being two small bathroom floors. The buffer is only warmed during the heating season, today and most of the summer solar or the DHW module provides DHW.

I do have a solar pre-heat tank so the Cadet DHW module does always see tempered water.

I'm also trying a SolarinCal valve from Caleffi. This assembly of 3 thermostatic valves selects between the boiler DHW or solar. If the solar tank is 110 or warmer the DHW module is bypassed. The valve also tempers the DHW should either the DHW module or solar tank exceed 113F.
Bob "hot rod" Rohr
trainer for Caleffi NA
The magic is in hydronics, and hydronics is in me


  • heatpro02920heatpro02920 Member Posts: 991
    edited May 2013
    I have been thinking about trying a few cadets

    the smaller unit that goes sub 9K is very interesting since the WBN051 is gone, the whn055 does go down to 11 but its cost is pretty high for what you get... but the 94% rating can mess with your rebates through national grid... may be a good option for the low heat loads that really want a wall hung boiler...

    Nice install, I love when boilers are mounted on painted plastered walls, it take the "dirty" out of what people think about heating systems...
  • SWEISWEI Member Posts: 7,356

    is indeed the interesting one for us  Looking to see what kind of deal we can get on them for next season, but would love to have a firsthand report from someone before we jump.
  • heatpro02920heatpro02920 Member Posts: 991
    Same thing Im thinking, Swei

    I don't want to start throwing them in to learn what issues they have, I would much rather have someone else learn the hard way, even if it means being a little late to the table....

    A couple things that I would like to see changed, 95% rating would be nice {the rebate for 95+ is 1500 around here otherwise you just get the 90+ rebate...} next is the heat exchanger, I would much rather see something closer to the TT design or the knight, but for the cadet price Im sure its a decent unit....
  • SWEISWEI Member Posts: 7,356
    We do think alike

    But at 2.1 GPM and 3.9 ft of head I can live with it.  Finding a small enough pump is the challenge there -- I'm looking at the ecocirc e-series for them, but will need to figure out how to pipe them so they can be flushed and serviced.  What we really need is those metric union threads all the small EU pumps come with, but everything here has flanges.  A union on one side and a Webstone union ball drain on the other might work...

    The biggest question (other than stability and reliability) at this point for me is cost.  The generic contractor price I got from the rep is slightly more than what we pay for a PTS60.  If the "bought right, shipped right" deal for distributors allows them to sell it for what I hope it does, we may have a winner.
  • hot rodhot rod Member Posts: 7,011
    union pumps

    and fittings? Let me know what you have in mind, we have union style pumps in our hydronic and solar modules and plenty of fitting and valve assemblies to "mate" them. An ECM circ may be a good option for your idea, low flow and low current draw.

    I installed this Cadet with a 132 flowsetter so I can see the actual flow at different pump speeds on the 15-58. I may just squeeze an Alpha in and get sufficient flow on this 120, spec shows it to be close, sometimes actual flow differs from the data on paper :)

    Once you get use to union style circs they are nice to install and manage. A 10" slip joint pliers is all you need to install them, a 10- 15 second task.

    And when you embrace union bodies a whole new selection of circ sizes and types become available, like ECM solar pumps, PWM drainback, GEO, and hydronic pumps, and sizes that are not available as flanged.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • heatpro02920heatpro02920 Member Posts: 991
    Off the top of my head

    I would install a webstone for cleaning the HE... I have made this common practice on the units with problematic HE's. Also a fast fill bypass under the psi reducing valve. The purge and fill valves are nice, I made a high pressure/flow pump to clean HE's, just hook it to the purge fill and let it run through the HE, also works nice for cleiang the systems before installing a unit, its just a 1/2hp jet pump with the rite fittings to hook it to a couple 3/4" Heavy duty braided hoses...

    Webstone is making some nice stuff, Im sure watts, taco, ect will be catching up, but for now webstone is the one... I use there 1x1 sweat purge tees for hyd. sep. all the time...
  • SWEISWEI Member Posts: 7,356
    Webstone rocks

    Great products, fair pricing, constant innovation.
  • SWEISWEI Member Posts: 7,356
    Metric union pumps

    What can we actually buy here in terms of small ECM union pumps?  Stratos Pico never made it as far as I know, and the true microcircs are even rarer.

  • heatpro02920heatpro02920 Member Posts: 991
    I wish they

    made a 1-1/4"X1" purge tee in the opposite figuration than what they offer, they have the 1 1/4" on the run and the 1" , but the opposite would make it great for the larger mod cons...
  • ced48ced48 Member Posts: 383
    For $500 More-

    the Loch 55 seemed like a better buy than the Cadet 40. The HX and the 55's computer seemed like they were worth the $500 alone.
  • SWEISWEI Member Posts: 7,356
    and there is the issue

    if they can find a way to sell them for $500-600 more than an equivalent output CI boiler they will have a winner -- as long as they don't develop some form of midlife meltdown or require inordinate amounts of service in order not to.
  • heatpro02920heatpro02920 Member Posts: 991
    I think

    we are a long way from a sub $2K mod con no matter how small they make it. We are stapled to cast iron in that sense, but I don't mind, until mod cons have a 30 year heat exchanger {yet to be proven and not off to a great start} and a universal connect control {1 control that can control them all with universal sensors {kind of like a ci boilers aquastat, just plug it in and only stock 1 or 2 different models} I don't mind keeping cast iron boilers in the line up...

    But someday I'm sure we will be replacing them as Dinosaurs and bolting in something that weighs around 100lbs, plugs into a wall receptacle, vents out a 3/4" flexible duct, with a bunch of wireless t-stat modules you control with your cell phone that is implanted into you eyebrow.

    I'll never forget the face of one of the old timers I learned with, when he seen his first digital thermostat, I remember it was a HUGE Honeywell, the buttons said "ahead, back, warmer, cooler" and it had a big flip up door and a display you had to bend down to eye level to read that looked like a calculator screen.... FANCY!!! And very intimidating to that tech, lol... I think he expected a 1/2 bundle of wires or something because he was totally against installing it.. He's passed now, but I'm sure where ever he is if there is a heater it has an RA117 stack relay, shell head burner, and a t87 mercury t-stat....
  • SWEISWEI Member Posts: 7,356
    Affordable boilers

    as you've pointed out before, ROI gets pretty ugly when you're heating only a few months with a small heat loss.

    Most of the magic of a mod/con comes from modulation, so why can't we have some of that US Boiler G-series iron paired with a modulating (or even a two-stage) burner?
  • heatpro02920heatpro02920 Member Posts: 991

    The closest you are going to see to that is using 2 of them boilers and making your own 2 stage system... We all agree sizing the load properly is the best thing we as designers can do for our customers, I do this a little differently, I will gladly add a heat pump to their a/c and under size their boiler with some type of aux. heat for when the installed system can not keep up on that once a year night {if that}.... In a perfect world an all in one system that did all of that would exist, a magical boiler that would have a heat pump built into it for days above 45*s and 2 stage modulation where it could fire either 7-30K or 30-80K BTUs... Not going to happen that would be like a magical animal that made ham, sausage, and bacon...
  • SWEISWEI Member Posts: 7,356
    edited May 2013
    hybrid systems

    and the control thereof is what I prefer to build, but I'm always looking for better answers.  We have several times the heating degree-days here as we do cooling, but the challenges for a small house (of which we have many) come from both cost and equipment space.

    I wish Daikin made the Monobloc Althermas in smaller sizes.
  • hot rodhot rod Member Posts: 7,011
    which union circ do you want?

    Generally the union pumps are OEM. But as you know most all of the solar pump stations have union pumps as do many of the radiant mixing stations, from various manufacturers.

    Really any pump module with Euro origins will more often than not have union pumps. .

    So from most suppliers you have access to Wilo and Grundfos. Wilo Star 16 & 21, Grundfos 15-58, Alphas, 15-100 high head drainback circs, larger Star 30 and 32. That should cover most radiant and solar pump applications.

    We are starting to receive the Grundfos Solar Series (yellow label) on the new Solar Pump Stations. I think those are 15-62, don't quote me.

    If there is a pump station or mixing station with a union pump, out there, then the replacement pump is also available.

    Generally if a pump fails, just the power head can be replaced not the entire volute. Wilo has just two allen head bolts holding the motor into the volute body, a very quick change out.

    Do the Vitodens use union pumps under the hood. I thought some of them has PWM Grundfos circs? probably in the Euro 230V style, hense the older style Vitodens requiring the step up transformer box.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • SWEISWEI Member Posts: 7,356
    union circ

    that we can control somehow, preferably ECM, similar in size to the little ecocirc or even the larger one.
  • hot rodhot rod Member Posts: 7,011

    any of the PSC circs can be controlled with the solar (differential) controllers, like the I-solar. While not a true PWM logic it does ramp from 30- 100%

    Larger circs can accept PWM signal now, but you need to buy that interface box from the pump manufacturer. Most of the solar controllers have an optional PWM interface box, but you still need the pump manufacturers interface box also, it gets complicated and expensive. we have a few large solar systems running Magnas with PWM.

    I think we are real close to seeing PWM pumps with those two additional control leads. I have some samples but they are Euro 230V. Getting that circ here requires some order commitment, voltage change and the ever time and $$ consuming UL approval for the junction box :)

    It sounds simplier than it is to bring in all the cool stuff from Europe. We are the only market, and a small one, that requires 120V motors on their circs.

    I think Europump has upped the ante and we will see even more efficient pumps then the current ECMs, at least in the European market. Eventually is may make it's way over here.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • SWEISWEI Member Posts: 7,356
    I can control them with a TRIAC

    for under $50, but there's the time and hassle of piecing it together plus the inefficiency of both motor and controller.  Those little ecocircs move water using almost no electricity and the variable speed dial is already there.  Just wish they'd give us a 0-10V input option for them.

    The switching power supplies used in ECM circs should be designed to run on 90-250V (like computers have for almost two decades.)  Even better if they extended the uper range to 300V, which would allow use on one leg of a 480 service.

    I've been using the Wilo Stratos on 208V here and have not had any dropouts yet.
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