Modcon with IHW Tweaking

Discussion in 'Boiler Forum' started by chris24, Jan 10, 2011.

  1. mage182

    mage182 Member

    Messages:
    71
    Location:
    NY
    Thanks for the reply.

    This question might go in a different direction. But if having burn cycles of at least 10 mins isn't short cycling, then is having the thing run all the time bad? The past few days (It's been cold with highs in the mid 30's, lows in the low teens) I've been seeing 60 cycles a day just for heat. I've noticed they're mostly for the zone with the living room, bathroom, kitchen on it. That would mean every hour the boiler runs 3 x 10 minute burns with 3 x 10 minute off periods. In a house that 's STUFFED with roxul insulation, vapor barrier, all window gaps foamed, shouldn't the heat not have to run as much considering I keep my tstats at 65?

    I have no problem with the unit running, I just don't want it to crap out in 5 years due to wear.

    As far as the cast iron baseboards go, I didn't use them in the first place because I don't have the compression fittings to attach the sections and I couldn't find end caps for them. I'll put more effort into that this summer.

    When I put in the fin tube last year I did a heat loss analysis to determine how many feet I needed for each room. Does that go out the window with the cast iron? Should I just cover all walls that are convenient which is mostly more than the fin tube covers knowing that it will add to the heating mass and keep the room warmer for longer resulting in less cycles for next winter?
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,261
    Location:
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    Cycles tend to wear things out faster than constant running.
  3. Dana

    Dana In the trades

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    The 140-200F BTU/foot specs for cast iron baseboard are very similar to run if the mill fin-tube (roughly 600BTU/ft @ 180F & 1-4 gpm flow.) Adding length is fine & good for lower the operating temp & increasing thermal mass mass, but be sure to add it proportionally for the rooms within the zone to ensure the room-to-room balance doesn't get all out of whack. See: http://www.usboiler.net/products/baseboard/baseray/assets/io-manual.pdf and http://www.weil-mclain.com/en/multimedia-library/pdf/weil-mclain-pdf/products/baseboards/snug-baseboard/en-snug-072011.pdf compared to http://www.slantfin.com/images/stories/Technical-Literature/ratings_fineline30_r.pdf The performance of fin-tube at sub-100F is off-the charts variable- dust-kittens & anything that can impede convection hurts it considerably. Cast-iron's heat transfer output at low temp is largely radiated heat, whereas fin tube's output is dead without good convection.

    Firing nearly continuously at or near the minimum burn rate is the holy grail of efficiency & boiler-longevity. If your minimum burns are 10 minutes that's GREAT for the boiler's lifespan. What kills a boiler in short years is running 20+ burn cycles per HOUR all season long. At 3 burns per hour when bumping off the bottom you're in excellent shape. Keeping the temperature down to where it's nearly always condensing will do wonderful things for efficiency. Since from empirical observation water temps are not reaching the ODR programmed temps before the t-stats are satisified it's clear that you have room to lower the curves, which should lead to even longer/fewer burns during the colder weather, when the heat load of the house is above the minimum-fire output of the boiler.
  4. mage182

    mage182 Member

    Messages:
    71
    Location:
    NY
    Update

    I spent a good amount of time over the summer working through the sandblasting, assembling, and painting of two different brands of cast iron baseboard. I took out all the fin tube (except the 2ft section in the bathroom) and replaced it with the cast iron. I found some paperwork on the output of the cast iron and found it to be less than the Multipak 80 I had so I installed a few more feet not only to match the numbers but for continuity since the cast iron is harder to install.

    The boiler has now pretty much ceased to short cycle at all. The heat is much more comfortable and even. When I expand I will make a point of sourcing more cast iron from Craigslist, or buying new if necessary.

    My two problem items going forward are:

    1. I have no end caps for the cast iron. I was hoping by using all brass fittings on the ends it would look nice enough to leave uncovered, but it doesn't. American Standard and Radiantrim haven't been produced for some time now so finding end caps is near impossible. I've drawn up a few designs I'm going to try with 1/4" oak veneered plywood hopefully using magnets to hold them on.

    2. I'm feeling heat in the rads close to the return side of the zones when the IHW zone kicks on. This is on priority so no other zones are running when making hot water. I'll start by saying there are no flow checks on the zones, only one on the zone for the IHW. What I'm thinking is happening is as the tank calls for hot water, the water is being pumped into that zone and drawing water back out of the other zones as the water flows through the manifold. This water is then being replaced at the other end of the zone as the water flows back from the tank into the return manifold and is also flowing into the zones on the return side. This is probably hurting my delta t numbers when the heating zones first come on as well as causing some unwanted heat.

    Are installing flow checks on the 'push' side right after the pumps enough? or do I also need them on the return side?

    I want to use swing checks, but from what I've read those have to be installed horizontally which would be a problem for me. If I need to install vertical would I need to use spring loaded checks? Those look like they hinder flow a lot and I've read comments about them chattering.

    Any input?
  5. Dana

    Dana In the trades

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    It's amazing what a bit of real-radiation and some thermal mass can do for comfort compared to fin-tube, eh?

    I'll let the pros comment on different types & orientations of check valves- there's not a lot of rocket science to it though. A worst case solution is to inserrt zone valves, which reliably block flow in any direction when the zone is off no matter how interactive/leaky the zone loops are. They reliably block parasitic convection that might otherwise occur with very-low-head check valves.

    Now that the boiler isn't short cycling you should take the time to dial in the reset curve and really max out the condensing efficiency.
  6. mage182

    mage182 Member

    Messages:
    71
    Location:
    NY
    Guess I spoke too soon. Woke up this morning to a semi cold house and a hard lockout code 25: Internal control failure. (Reset the control. If problem reoccurs, replace the Sage.)

    Blackman (supply house) says to call Burnham. Burnham says to call a local tech. I called the first 10 techs on the Burnham site that they list as affiliates and none of them work with the Alpine models.

    The only thing I found is this:

    http://www.heatinghelp.com/files/posts/10961/Burnham_Alpine_Bulletin.PDF

    Which I can do all of myself, although I doubt Burnham will send me that boot for free and if I want it I'll end up paying for it. I've found them to be very lacking from the customer service standpoint.
  7. BadgerBoilerMN

    BadgerBoilerMN Master Hot Water Mpls,MN

    Messages:
    303
    Location:
    Minneapolis
    We are a certified Burnham boiler dealer here in Minneapolis and specialize in the Burnham Alpine and other condensing boilers. The manufacturers are not set up for DIY as it is impractical -read impossible- to directly server thousands of retail customers lacking trade skills and tools. High efficiency condensing boilers are almost always the best fit for new construction or retrofit for natural gas is available but installation and annual maintenance is the key to safe, reliable, efficient space and water heating.

    An example is the short-cycling of the indirect water heater (IWH), we find as a common complaint. First in most condensing boiler software there are two settings, one for the potable water temperature in the tank and a second for the "design" water temperature i.e. the set point the boiler will try to maintain while heating DHW indirectly. This temperature is typically factory set to 180-190°F comfortably maintaining a differential temperature to assure efficient heat transfer. If boiler, pump and IWH are properly matched no cycling should occur, rather the boiler will start up to full-fire and gradually modulate downward until the call from the tank is satisfied.
  8. mage182

    mage182 Member

    Messages:
    71
    Location:
    NY
    Burnham won't do anything without a certified rep diagnosing the problem and then ordering whatever parts are necessary. So I sat down with the list on contractors on their site and started calling them and found that either they wouldn't look at an Alpine because they don't work with them, or they're still so swamped with calls from Sandy that they said it would be a while before they could schedule a call. I've been increasing the distance of the contractor from my location, hopefully I'll hear back from the ones I called this morning. The unit is only a year old so at least everything should be covered under warranty once I can get someone to come over.

    Badger, out of curiosity, how much would you normally charge for an annual maintenance call for an Alpine? Is it something that is required every year?

    Also, I was getting short cycling on the IWH, but after doing some calculations I was able to get it to cycle just once on a call in almost all cases. I adjusted down the max fan RPM. My question is, if the temp sensor on the tank has no communication with the boiler other than to call for heat or not (call it binary 0/1), how does the boiler know at what rate it should modulate downward in order to not short cycle before the call is satisfied? I had initially set up the tank at 180 degrees and set the max fan speed for that call based on the minimum boiler output on the tank spec sheet, but I was getting short cycling. Does that infer that the pump zone pump for the tank has a gpm rating that is too low?
  9. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,261
    Location:
    New England
    Most IWH sensors I've dealt with (and that's not many?!) are that they are thermistors which means, if they are calibrated to the boiler's control circuit, it knows what the water temp is in the tank. If it's just an aquastat, that would just be a switch. SOme aquastats have two switches in them, a high and a low, and it tries to keep things between the two, but it has no idea how far from the high (which would turn it off) or the low (which would turn it on) is.
  10. mage182

    mage182 Member

    Messages:
    71
    Location:
    NY
    Someone finally came to look at my Alpine. He said the control unit is fried from power surges during Sandy. He said that Burnham won't cover it under warranty and that I should have my homeowner's insurance cover that as well as the rest of the damage to my house. The only problem is that he has already ordered a few replacement control units and they are 6-8 weeks back ordered.

    He recommended I talk to my insurance company and see if they'll just pay for a new boiler.
  11. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,261
    Location:
    New England
  12. mage182

    mage182 Member

    Messages:
    71
    Location:
    NY
    I was thinking more something like this:

    http://www.tripplite.com/en/products/model.cfm?txtSeriesID=838&txtModelID=4910

    My uncle is an electrician and told me he would install a surge protector for the whole electrical panel that goes in the top slot of each bus on the panel. But that won't help with voltage regulation, only spikes.

    I haven't been able to find any economically priced hardwired voltage regulators. Is it acceptable to wire a standard 3 prong plug on to my feed to the boiler and plug it into this before going to the cutoff switch?
  13. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,261
    Location:
    New England
    My boiler is plugged into a receptacle, so at least where I live, it passed code.

    That device monitors the power, that controls a relay that can be used to disable operation if the power is out of range (high or low). Plus, if the power is flakey, it will not energize the relay until it stabilizes, and you can set a delay after it's stable before that happens. Adding whole house surge suppression would take care of the rest of the things. I have one in my HVAC system that disrupts the 24vac control voltages so that nothng can turn on until the power is stable. I rely on the whole house surge suppression to handle the spikes and noise, and this to protect the motors and compressor from severe brownouts.

    Depending on the panel, you may be able to plug a surge suppressor in as a CB-like device, or there are numerous panel surge suppression devices available with varying degrees of protection. I put one from Mersen (sp?) at my mother's house after she lost the control board in her frig and the microwave on the same day. There are a few threads discussing this you can read for thoughts - use search.
  14. mage182

    mage182 Member

    Messages:
    71
    Location:
    NY
    I ended up ordering this model

    http://m.tripplite.com/en/model.cfm?txtModelID=208

    It should be here Monday so I'll wire it up then.

    I ended up getting a new control module thurs. I ordered it from a supply website and they happened to get one in stock. I swapped it out and the new one works. I put in all my old parameters. However, the repair module works with all models of the boiler so you have to pick the right one (it comes defaulted to the 80 model). I found that you need a factory password to change this which I don't have. Burnham would not give it to me and the same tech I had come over last time told me it would be at least 2 weeks before he could come over.

    Does anyone know the 'factory password'?

    Is it bad to run the boiler with the model set to this setting?
    Last edited: Dec 1, 2012
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