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New boiler install G115 and controls questions

vilord Member Posts: 48
edited June 2019 in THE MAIN WALL
I am finally getting our old leaking Burnham V7 replaced with a Buderus G115 (yay!)

Our installer has done a few things that I'd like clarification on.

1: The circulation pumps:
On most installations that I have seen, the TACO 007 pumps were set up on the returns, pulling cold water out of the baseboard loops and drawing the hot up as a result.

Our installer set up the pumps on the *supply*, pumping hot into the loops.
Will this cause our pumps to wear out faster? Do they care? And, do they have a "correct mounting orientation? Some are mounted horizontally, some vertically.

2: On our burnham, the supply and return had a pipe running between them, which i guess caused it to heat the manifold faster or something.
On the GB142 I have at my other property, the manifold *is* a loop, with its own multi-speed circulator
Here, the installer did not install any loop directly on the manifold, and the circulation happens only when one of the heating or DHW loops is calling for heat.
Is this correct for G115?

3: Our installer put in a Fuel Smart "Hydrostat" aquastat that apparently has algorithms and programming to calculate how long a zone is calling for heat, and it will ramp up the target boiler temperature based on that algorithm. No outdoor reset sensor, no indoor reset sensor.
Any idea how much of an efficiency change I would see if I upgraded to a 2107 or tekmar system with indoor/outdoor reset?
Also, has anyone used one of these with a radiant loop? I want the algorithm to be bypassed when running radiant obviously, as the radiant loop might call for heat for hours.

As a note, my experience with outdoor reset hasn't been great... I have a Tekmar 260 outdoor reset control that i used with the V7, but saw basically no efficiency change because we used to have an air handler that required a minimum of about 170 degrees to put out any useful heat... we've gotten rid of the air handler and are now just baseboard + radiant.
At the other property, when I had outdoor reset added to the GB142, I saw heating bills go up. Possibly due to older inefficient baseboard that wasn't getting hot enough to convect.

Thanks all!
Alan Welch


  • Solid_Fuel_Man
    Solid_Fuel_Man Member Posts: 2,646
    The pumps on the supply is absolutely the best location! Pumping away from the expansion tank will help with air removal and minimize the potential for pump cavitation.

    I dont like to ever mount them with the shafts vertical, it is permissible if the system is over 20psi, but that is high for a typical residential system.

    You dont need the bypass loop with a Buderus with low mass baseboard.

    As far as lack of outdoor reset, I cannot speak to efficiency gains, it really depends on how much (if any) excess radiation you have and how low of supply temps you meet to maintain indoor temps. I generally dont see much gain with baseboard, completely different story with radiant, outdoor reset is a must.
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
  • vilord
    vilord Member Posts: 48
    You mention that the bypass loop isn't needed for low mass baseboard... We also have one 18x22 in-slab radiant loop.
    Will that cause the return water to be too cold for too long and need a bypass loop?
  • vilord
    vilord Member Posts: 48
    edited June 2019
    Also, thanks for the pump info! Glad to hear this is a decent setup. I like this company/these contractors and want to recommend them :)
    (The pump shafts are all horizontal, the flow direction is mixed horizontal and vertical)
    HVACNUT Member Posts: 5,832
    Can you post some pics of the system. Other than the radiant zone, I can't see why the circs aren't lined up pretty. We'll also be able to see if all pumping away piping and controls is correct. You'll notice the return port on the block is only 1 in. That's one of many things Buderus uses to help prevent thermal shock to the block.
    If it's in the budget to add the 2107, I'll never say no. The 3250 Plus is a nice control and I'd use it in a second on any other boiler, but the 2107 with a G115, G215, G315 will better manage your home, especially if you have multiple SWT zones.
    The thing is, as an owner, you, as well as your service contractor really need to know how to operate it. You seem like your able, so if all else fails, flip it to manual. That will buy you time to Check the I&O manual and/or make a call.
    What size G115?
    What burner?
    What supplies the domestic hot?
    Pics please.
  • vilord
    vilord Member Posts: 48
    edited June 2019
    First, apologies that I write so much!

    We have 3 baseboard and 1 radiant zone, DHW is a 92 gallon solar indirect (we have about 40 or 50 sq ft of solar water).

    2 sections of baseboard are from the 80s, the rest is new this month.

    G115WS/5 with a Riello R40/F5.

    The radiant zone (a small section in an isolated space in the house) is currently wired to the TACO zone relay panel, which means it will be calling for heat any time it is running at full boiler temp, which is a huge waste since it only pulls 105-120 or so through a mechanical thermostatic valve (i still don't know what benefit an electronic mixing valve would provide...). For now I'm going to have the contractor put it back on its own relay and draw whatever leftover heat is in the boiler from when the rest of the house calls for heat, and not actually call for hit. This has worked okay for years...

    I don't like the solar controller, and I have a feeling it is not configured well... we seem to run the boiler far more than we should in the summer.

    The 3250 doesn't support dual temp targeting, so i can't tell it to do something different with the radiant.

    There is a new in box logamatic 2107 for 500 bucks near me. If I buy it this weekend, I can have the contractor swap out the 3250 and knock that off our install bill, and then I can add on the mixing card later, possibly also the solar card.

    I see some other folks on here don't like the 2107 and find it either overly complex or unreliable or both...

    Full boiler view (with my old disconnected 260 in the background):

    Baseboard and DHW pumps:

    Radiant loop with thermostatic mixing valve:
    (pump is within the radiant loop, pulls in from just above the boiler output before the air separator)

    Boiler & zone controls:

    Pex/copper running to the brand new baseboard:
    (is this method of "splitting" a thing now? I've always seen everything connected in series)

    DHW tank:
    (Wagner integrated drainback solar system)
  • vilord
    vilord Member Posts: 48
    edited June 2019
    I realize that some things look messy and there's a bunch of pipe that needs insulation, the guys aren't done yet, they just hooked up the DHW zone today so we'd have hot water for the weekend, the rest are still charged with air for leak testing.
  • Solid_Fuel_Man
    Solid_Fuel_Man Member Posts: 2,646
    What kind of black pipe is that for your radiant? Onyx maybe? Just looks like HDPE in the pics.
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
  • vilord
    vilord Member Posts: 48
    Actually the black pipe is AlumiPEX that runs to the new baseboards. The radiant was installed in the early 80s before pex was as mainstream.