New Home owner - needs heat - Oil and electric available DYI

Discussion in 'Boiler Forum' started by dremodeling, Sep 11, 2013.

  1. dremodeling

    dremodeling New Member

    Messages:
    2
    Location:
    Philadelphia
    Hello , I came across your forum , spent hours to search for an answer and even if I found a tone of useful info .. I still have questions.
    Please help :

    I just purchased a house - the house had oil and hot water baseboard radiators. In the same day when I had the closing - someone steal all the cooper ( including cold and water feed and all baseboards ) ... I was planning to replace the baseboard radiator no matter what - however now I am forced to do a lot of plumbing..

    I am trying to be as efficient as possible - however I am not sure what is the best ( most efficient ) option for me at this point . Here is some data

    1) House is in Philadelphia area; split level , 2,000 SF , 4 bedrooms 3 bathrooms.
    2) I do NOT have gas.
    3 ) I have an oil tank but no furnance
    4 ) I have AC unit in the attic ( duct's already in place )

    My thoughts are :

    1) Hot water heated floor on the 1st level ( open floor plan - kitchen , dinning living room - with access from basement )

    2) Radiators ( buderus panel radiator ) in each of the other rooms 3 bedrooms on the second floor and two bathrooms , plus a master bedroom and a bathroom in attic .

    My questions are :

    1) What I should use to heat the water?
    I do not have a furnance right now

    A furnance ? a boiler , ? a water tank ?

    Same system to heat the house and for domestic or two systems ?

    What brands ? what size ?
    2) How I can calculate how big each radiator should be ?

    3) The heated floor in the 1st floor will be enough ? how I can figure out the BTU output from a PEX system

    I am a terrific DIY if I have the correct instructions,

    Can someone help me out ? It is anyway to find someone who can tell me exactly what I should do and what I should use ?


    Excuse my GRAM , english is my second language !!

    And THANK YOU in advance
  2. Murphy625

    Murphy625 Member

    Messages:
    155
    Location:
    Michigan
    I don't mean to sidestep your question but why not just file an insurance claim?
  3. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,306
    Location:
    Maine
    Terrific DIY or not that's a pretty big undertaking and nearly impossible for anyone to instruct you on the proper sizing and installation in a DIY forum. Bite the bullet and call a professional.
  4. Dana

    Dana In the trades

    Messages:
    3,018
    Location:
    01609
    In a Philadephia climate and electricity prices ductless air source heat pumps cost less than half to heat the place than heating with best-in-class oil burners at $3.50/gallon from an operating cost point of view. For the all-in full lifecycle cost including equipment financing/replacement/maintenance it's about 60% of the cost of oil. Whether there's a workable & affordable solution depends a bit on how open the floor plan is, and the actual heat load at Philly's +15F 99% outside design temperature. See this recently published policy piece on the topic.

    If it's too doored-off to deal with ductless, it's likely that the 3-ton variable-speed Carrier Greenspeed could handle both the heating & cooling loads at reasonably high efficiency at about half the cost of heating with oil, but it's probably more expensive than 2-3 head ductless solution.

    AC with ducts & air handler in the attic is grossly inefficient at ANY nameplate SEER efficiency, since it puts the ducts outside the conditioned space, and punches holes for parasitic infiltration in the pressure envelope (upper floor ceiling/attic floor), then DRIVES infiltration by creating pressure differences between rooms. On a house that size that configuration for AC adds on the order of a full ton of cooling load. If that's the only possible location for the ducts, the (fairly expensive) solution is to insulate the attic at the roof deck and go with an unvented attic. But to do that without risking moisture damage at the roof deck code requires at least R15 of the code-min R-value to be exterior to the roof deck (say, 2.5" of rigid polyiso foam), or as high density foam insulation on the interior (2.5" of closed cell polyurethane, or 3" of 2lb density open cell polyurethane, eg Icynene MD-R-200.) That portion alone will run about $3 per square foot, before you get to the fiber insulation, but done right can reduce the overall air infiltration (and heating load) significantly.

    All heating & cooling solutions start with a careful room by room heat load calculation using realistic indoor temperatures and the 99% outside design temperature. Resist the urge to overestimate the heat losses- even ACCA Manual-J methods have an inherent error to the high side, and oversizing the equipment by a large margin leads to more money up front, lower operating efficiency, and lower comfort. This is not a half-hour calculation, and it may be worth paying an energy nerd to do the measuring and calculating independently of the HVAC contractors, many of whom are prone to using easy rules-of-thumb, methods that reliably oversizes the systems, which is NOT what you want.

    Don't be surprised to hear suggestions like "Let's see, 2000 feet times 25 BTU/foot comes to 50,000 BTU/hour, but let's bump that to 70,000, just to be sure." In most homes that are reasonbly air tight, have doube-pane windows (or single pane + storm windows), and any reasonable insulation, the real heat loads will be under 20 BTU/foot of conditioned space, and many will come in under 15 BTU/foot. You have to make reasonable calculations based on the actual construction to know for sure where it really lies, but the last thing you need or want is 70,000 BTU/hour of heating equipment output for what could very easily be a 28-30,000 BTU/hour heat load.

    If you know your window types and their area as well as insulation types & thicknesses and the wall & attic areas, you can use a standard spreadsheet tool like Excel using classic I=B=R methods for estimating heat loads and achieve reasonable accuracy.

    Only when you know the room-by-room load can you make reasonable judgments on the necessary equipment for meeting those loads.
  5. dremodeling

    dremodeling New Member

    Messages:
    2
    Location:
    Philadelphia
    Hi I am actually a contractor - but not a plumber or a mechanic...

    I can definitely to everything myself... and even if I can hire someone .. I am to proud to do that ( not a matter of money ) .

    The goal is to make the house as efficient as possible ..

    - I will put foam in all exterior walls, replace all windows.. and doors.

    I just need someone to design the best system for me ...

    Do you think I should ditch the oil and stay electric only ?
  6. Dana

    Dana In the trades

    Messages:
    3,018
    Location:
    01609
    Going with heat-pumps and electricity is less expensive to operate, and if you use variable-speed types (either ducted or ductless) the comfort levels are quite high. Keeping the oil tank around until it leaks is nothing but a liability, and there is no realistic projections for increasing worldwide oil production keeping up with the pace of increasing demand with the growth of the Chinese & Indian middle classes driving cars.

    What's more, on a 2000' house that has any decent window and at least some amount of insulation (even below current code minimums), even the smallest oil burners have twice the output that it takes to heat the place, and on a house that you are upgrading to better-than-code would be even smaller still. With a good designer it's possible to get the heat load of a typical 2000' split level "raised ranch" down to 15-20,000 BTU/hour if you're willing to replace all the windows, and add continuous rigid insulation under the siding.

    Making the house "as-efficient-as possible" has many meanings, and costs. Closed cell foam is expensive and largely wasted when used between studs, due to the thermal bridging of the studs. Using open cell foam or cellulose between the studs, and adding 2-3" of rigid polyiso on the exterior, between the sheathing and siding may cost about the same if you were planning to replace the siding and windows anyway, but you'd have less than half the heat loss through the walls that you would with 2x4 framing full of closed cell foam. Start here for more information on how that's done.

    It's impossible to "design the best system" for heating and cooling until the heat losses and solar gains are known, and that can't happen until you have the U-factors & areas for the windows & doors, and the U-factors of the wall, foundation, and attic assemblies, which are a function of both their construction & insulation types.

    For example a 2x4 wall with 3.25" of closed cell foam in it with at a typical 25% framing fraction, with wood sheathing and half-inch sheet rock comes in at about R11 after accounting for all thermal bridging, which is a U-factor about (1/R=) 0.09 BTU per hour per square foot for every degree-F of temperature difference. So at an interior temp of 70F and a 99% design temp of 15F that's 55F degrees for (55F x U0.09=) 4.95 BTU/hour for every square foot of exterior wall.

    If you take the same 2x4 framing, fill it with 3.5" of open-cell foam or cellulose, it's not very different, about R9.5, for a U-factor of (1/9.5=) 0.105, times a 55F difference is 5.78 BTU/hr for every square foot, a difference, but not a big difference.

    But if you then added 2" of polyiso (R13) on the exterior of that cellulose or open cell foam wall and re-side it with an air gap between the siding and foam, after thermal bridging is factored in it'll be about R22, for a U-factor of (1/22 =) 0.045 per degree-foot. Times 55F that's 2.48 BTU per square foot.

    That's literally half the heat loss with the 3.25" of closed cell foam between the studs, but at a comparable installed price. And in that assembly you wouldn't need or want an interior side vapor barrier (no poly sheeting, no asphalted kraft paper), since the wintertime temperature of the sheathing would never be cold enough to absorb moisture to promote mold growth.

    Windows all have published U-factors. Code-maximum in PA is probably U0.35(?), but if you are going for a high efficiency house with R22 or greater walls window losses would dominate the heat load numbers. While it's possible to spend a lot of money on triple pane windows with U-factors of under U0.2, better low-E gas filled double-panes in the U0.24-U.028 are more affordable, and would be appropriate here, maybe with U0.30-0.32 windows with SGHC (solar gain factors) on the south side for passive wintertime heating. Avoid high gain windows on the east or west side, since that would dramatically increase the air conditioning loads. On the south side it's possible to install awnings or design roof overhangs to limit mid-day gain in the summer, but still have good gain in the winter when the sun is lower in the sky.

    There are other issues to attend to for insulating attics and foundations (which really DO need at least wall insulation, even in a code-min house), but it has to be done in a manner that manages the moisture migration issues cleanly too. If you want to read up on it, there is a lot of information on the Building Science Corporation website on assemblies that work from both a thermal and moisture point of view. As a starting point for where the costs of going higher-R might begin to lose a lifecycle-cost rationale from a purely financial point of view, see Table 2 page 10 of this document. Philadelphia is in US climate zone 4, so read the row for zone 4. Bear in mind those R-values are "whole assembly" values with all thermal bridging of the framing factored in, not center-cavity values on studwalls. (An R13 3x4 studwall comes in at only R9.5, as previously outlined.) The R25 wall structure starting point they recommend for zone 4 could be done with 2.5" of exterior polyiso on a 2x4 wall insulated with fiber or open cell foam.

    Bottom line, it's up to YOU as the rehab builder-designer to set the heating and cooling loads, THEN it's possible to specify the right heating & cooling equipment.

    But it's totally possible in a major rehab to size higher-efficiency air-source heat pumps to low loads, and impossible to correctly size an oil-burner to the load of even most code-minimum houses.

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