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Trouble with Multi-Zone Propane Heating

embrauer Member Posts: 2
I live in a newly constructed house and have been having trouble keeping the house heated to a reasonable temperature (~68F) and have a number of questions about my propane heating system. Let's assume for the time being that because the house is new, the insulation good and there are no obvious drafts. I live in Canada so winter temperatures can dip to 0F. Hot water is OK, so let's ignore that for now.

First of all, the setup:
- The house is about 2300sqft, divided in to three heating zones.
- Bosch Greenstar 100 (ZBR28-3A) propane boiler. With FW200 control module.
- Zone A is 3 bedrooms + 2 bathrooms with a single non-programmable thermostat. Baseboard heaters.
- Zone B is open-concept living room and kitchen, single non-programmable thermostat. Convection heaters. One "kick" heater in the Kitchen, and 1 floor heater in the living room (Myson Whispa III 5000 FM).
- Zone C is the entire ground floor, in-floor heating. 3 separate non-programmable thermostats in the office, garage and rec room.

The first obvious problem is that the FW200's outdoor temperature sensor is not working, it is either constantly at -40F or the FW200 is giving me a specific error that the outdoor sensor doesn't work (Fault 15). I am obviously trying to get this replaced, but I'm not sure if this problem specifically would be preventing the system from heating the house properly. If nothing else if the system thinks it's -40F outside it would provide MORE heating (and less efficiency), not less.

Overall, the house simply does not heat up very well at all. Zone A heats reasonably well, but it still takes well over an hour for the heat in to go from 60F to 70F. Zone B, where we spend most of our time, never gets above ~63F, no matter what we crank the thermostat to. The boiler just keeps running, and then convection heaters just keep trying. They pump out hot-ish air, but not enough to heat the space. Zone C, all three areas, is also extremely slow to heat up, and the garage will never get above ~61F even if I leave it heating for hours. I can tell there's hot water flowing through the in-floor pipes, but with little effect.

The FW200 is set to provide a have a max supply temperature of ~165F. There's a temperature regulating valve on the in-floor heating loop to ensure the temperature isn't above 100F to avoid damage to the slab.

I've attached a photo of the heating system (also here: http://i.imgur.com/uUU5Bri.jpg). The circulation of water flows counter-clockwise. This is different than the diagram on Page 54 of the Greenstar Application where the flow is clockwise. (http://www.prowaterheatersupply.com/PDFS/Bosch_Greenstar_Applications_Manual.pdf). Because of the counter-clockwise flow in my system, the supply water flows past the return pipe, which seems a bit odd. Is that normal?

My second question is how the FW200 actually works. Should I leave it on COMFORT or AUTO? With AUTO if I set up a schedule, how does that interact with the thermostats? If the control is on Frost mode in the middle of the night, and I manually turn up a thermostat to 68F, will that over-ride the current Frost mode the boiler is on, or does the boiler still limit the supply temperature (and therefore have a difficult time heating the house)? Basically if I set all thermostats to be 60F overnight, then is there any difference if the boiler is in FROST mode versus COMFORT mode? Which means setting up an AUTO schedule seems pointless if the thermostats always determine whether the boiler is on or not. The Application Manual says "ensure the mode selector is set to AUTO" for the type of application I have which confuses the whole issue for me.

Ultimately even if the boiler is on permanent COMFORT mode, the system still has trouble heating the house.

I generally leave the downstairs Zone C in-floor heating to 60F all the time since we aren't down there often. Could I improve the efficiency and efficacy of heating the upstairs if I heated the downstairs a little more at let that air rise upstairs? I doubt it would be more efficient, but I'm obviously no expert.

The last un-answerable question which I will ask the installer is whether the system is simply under-sized for the house.

Thanks for reading this long-winded post!

Here's the photo of the system if the attachment doesn't work: http://i.imgur.com/uUU5Bri.jpg


  • Paul48
    Paul48 Member Posts: 4,469
    It's piped bass ackwards.
  • icesailor
    icesailor Member Posts: 7,265
    Paul48 said:

    It's piped bass ackwards.

    Does anyone ever read the installation manual?

    More importantly, do they understand what they are reading about?

  • Paul48
    Paul48 Member Posts: 4,469
    I'd be very concerned if this installer converted to propane in the field.
  • icesailor
    icesailor Member Posts: 7,265
    edited December 2014
    If it was Nat Gas and it was improperly converted, it would sound like a flame thrower and smoking like a pot head.

    Other than it is firmly attached to a sheet of plywood, and it isn't leaking, can you find any other redeeming factors?

  • Paul48
    Paul48 Member Posts: 4,469
    I can't see it in the picture, but I wonder where he put the supply temperature sensor, since he's pumping off the return. It's ridiculous to think that he doesn't catch that if he just looks at the manual.
  • icesailor
    icesailor Member Posts: 7,265
    First, you have to admit something is wrong, then look at the hated manual.
  • Paul48
    Paul48 Member Posts: 4,469
    To the OP.......You need to contact the builder. The boiler must be installed to factory specification. All peripheral equipment(such as the air scoop), must also be installed per the manufacturers instructions.
  • embrauer
    embrauer Member Posts: 2
    Paul48: The supply temp sensor is on the vertical supply line coming out of the boiler. But according to the installation manual, it is in the wrong spot. Given that it's supposed to measure the supply temperature for the actual heating circuit, it should be on the horizontal pipe, downstream from where the boiler's supply feeds the circuit, as close to the T as possible, but still on the horizontal pipe.

    I suspect its current placement is causing the boiler to work very ineffectively. See attached photo, it's held onto the vertical supply pipe by the double zip-ties and has a blue wire. This might be causing the boiler to turn off pre-maturely based on the fact that it's measuring the temperature at a spot where it will always be hotter than where it should actually be measuring?

    My guess is: when the thermostats upstairs demand more heating, the boiler will generate some hot water and then at some point say "i'm providing enough hot water based on my incorrectly placed temperature sensor" and the thermostats upstairs are saying "no, the water we're getting is not hot enough, keep running!" In the end the supply water temperature will never be hot enough because the boiler only ever measures the temperature of the water before it mixes.

    Either way, we'll see what the installer says this week. Thanks for the comments and confirming my suspicions.

  • Harvey Ramer
    Harvey Ramer Member Posts: 2,239
    edited January 2015
    An uninsulated sensor on a steel pipe is not a sensor at all. You need some insulation wrapped around it.

    And I also concur the good folks above. The system is plumbed backwards and the boiler won't run at full capacity until the piping is changed.
  • icesailor
    icesailor Member Posts: 7,265
    "" I suspect its current placement is causing the boiler to work very ineffectively. See attached photo, it's held onto the vertical supply pipe by the double zip-ties and has a blue wire. This might be causing the boiler to turn off pre-maturely based on the fact that it's measuring the temperature at a spot where it will always be hotter than where it should actually be measuring? ""


    A round thermistor, with 1% of its area on contact, in a vertical pipe, with cold draft air flowing around 50+ percent of the circumference of the tube, measuring a fluid traveling in a circular motion with the hottest in the middle? And they don't put a piece or two of split Armaflex insulation held in place with zip ties?

    Then, if he moves it, he'll put it on the BOTTOM of the horizontal pipe where the fluid in the pipe is cooler.

    Extreme Sadness.

    "There's never enough time to do it right. But always time to do it over.

    Some people are clueless as to how to do it right.