Help w/replacement standing pilot valve

[estone]

I have a Honeywell standing pilot gas valve for a 1991 Burnham boiler. It needs to be replaced because it isn't fully closing and I would like to save some $$ by ordering the part online adn replacing it myself.
The current valve is #VR8300C4126
Honeywell obviously doesn't make this one anymore but I can't seem to get their website to give a direct replacement. I tried calling Honeywell but they won't help me figure it out because I'm not a contractor.

The one I was looking at was a VR8300C4506. Would this be a good replacement? The other numbers w/ 3/4 inlet/outlet they show are VR8300C4516, 4557, 4035, 4501.
The other ones on their website only differ by inlet/outlet size, opening characteristics, and pressure regulator setting. I'm assuming my older one(1991 or so) isn't a step opening? Any idea which one would be best for me?

Last question: I feel fairly confident that I can switch this out myself. Any reason why I shouldn't do it and find a plumber to do it? Other than I could blow up our house.

[Dana]

I can't comment on whether the part would be the right replacement, but in many locations a DIY is strictly prohibited. Even plumbers without a gasfitter certification wouldn't be allowed to touch it in my state. Any liablity for later issue (even 10 years down the road) would fall on you, and wouldn't necessarily be covered by insurance.

Also, with any 20 year old boiler I'd take a hard cold look at it's general condition, including inspecting the heat exchangers before pouring much repair money in it. Most are oversized to the point of being well below their rated AFUE, and if it's got less than a decade left in it you may be much better off pulling the trigger on something "right sized" or higher efficiency (especially if subsidized) sooner rather than later. (I retired by > 4x oversized 1991 Burnham P206 last year, and don't miss it a bit, even though I probably could have kept it for well OVER 10 yearrs with a modest repair budget.) The replacement is considerably smaller, quieter, runs longer & more efficiently, overall comfort is better, etc., and cost less than what another 2 decades of repair & maintenance would have been.

But it's your house, your budget, your choice, and I understand that first-cost on a whole replacement can be daunting.

[estone]

Any suggestions on Brands or models if we did replace the boiler? Current model is Burnham P-206A-WNVH.

[jadnashua]

The first thing you probably want to do is to have a heat loss analysis either done for you, or calculate it yourself. Older installations were notoriously oversized. This wrecks any efficiency you may have had and is tougher on the equipment as well (more on/off cycles). Then, indicate how the existing system is setup: multiple circulators, zones, type of radiation, levels, etc. Would you want the system to provide hot water via an indirect WH? How many baths/showers, etc.? Check your local utility supplier to see what incentives, if any, they are currently running. That may give you a big rebate, depending on what you choose. This can make a less efficient system more expensive to buy and install than a better one, given the incentives to conserve. That's not counting the long-term savings that can be had by a more efficient, correctly sized unit. When I replaced my unit a few years ago, I ended up with a Buderus mod-con, wall hung unit. My heating bills went down about 25%, and my old unit wasn't that inefficient, either. So far, quite efficient, quiet, and trouble-free. There are others out there. Depends somewhat on what's available in your area and what the installer is comfortable with. Mine feeds a mix of hydro-air, and radiant floor, plus a priority zone for an indirect WH.

[Dana]

What Jim said- a heat-load calc comes first.

If you have a mid-heating-season gas bill with the meter reading dates and we can correlate that with weather data for your ZIP code it's possible to do a pretty good whole-house load estimate of the design condition (coldest night) heat load. And work from there.

Unless you live in a moderately large & leaky house or a very cold climate it's likely to be 2x oversized for your peak loads, but the gas bill, location, and heating degree-day data will tell all.

The type & amount of radiation you have may also play into which boiler(s) make(s) the most sense.

[estone]

Our nat. gas bill is: $100(high, Jan.), $20(low, July). Our boiler is the only unit on gas. Obviously heats our water too. We live in a 1950's, 2100sq ft. ranch style home in Eastern Colorado(80723) with decent older windows and doors. Attic and floors insulated w/an extra 4" blown in attic. Small, finished basement. Our boiler is 160,000 btu(Burnham P-206A-WNVH), 80% efficient if I'm not mistaken.

I'm leaning toward just replacing the standing pilot valve(VR8300C4506) online for $100 myself and calling it good. Maybe it is oversized? but I can't see spending over $3000 right now, considering our gas bill really isn't that bad.

[estone]

Just to clarify.....Main level: 1344sq ft., basement, 784sq.ft., = 2128 total sq. ft.

[jadnashua]

Need to know how many therms or 100cuft of gas used to make a calc. A known amount of gas produces a fairly fixed amount of BTU's, so you can calculate what it took to heat the house. Knowing the rated AFUE (or efficiency) of the old unit would help, too.

[Dana]

Our nat. gas bill is: $100(high, Jan.), $20(low, July). Our boiler is the only unit on gas. Obviously heats our water too. We live in a 1950's, 2100sq ft. ranch style home in Eastern Colorado(80723) with decent older windows and doors. Attic and floors insulated w/an extra 4" blown in attic. Small, finished basement. Our boiler is 160,000 btu(Burnham P-206A-WNVH), 80% efficient if I'm not mistaken.

I'm leaning toward just replacing the standing pilot valve(VR8300C4506) online for $100 myself and calling it good. Maybe it is oversized? but I can't see spending over $3000 right now, considering our gas bill really isn't that bad.

The standing pilot version of the P206 has an AFUE of 78%, but a steady-state thermal efficinecy of ~80.5%. At your level of oversizing it's probably getting 70-75% AFUE maybe less.

If your January gas bills are $100, unless you're paying 10 cents/therm or something your peak heat loads are a tiny fraction of the steady state output of this beastie. (or did you mean $1000?)

To do the heat load calc we need the exact dates of the meter readings, the zip code, and the fuel used (in therms/decatherms/ccf or however it's billed by your utility.) Dollars mean nothing, since there isn't a fixed $ to BTU definition (natural gas prices vary from year to year, location to location by a HUGE amount.)

While square footage of the house is completely irrelevant to a heat load calculation, in almost ANY insulated house of any shape or size in the lower 48, a ~1400' s.f. house would have a peak heat load of less than half the 136KBTU output of a P206 (and probably less than a third unless the house is very leaky to air infiltration.) The surface area and R (actually U) values of the exterior surfaces (including windows & doors) and the 97-99th percentile coldest heating season temperatures are what counts for the calculation, and that will vary widely with construction type, window type (and size), etc between homes of identical square footage. There are too many measurements to take to do a room-by-room calc via web-forum, but with burner efficiency and fuel use correlated with heating degree-day data for a billing period with a significant heat load you can get remarkably good numbers on the whole-house heat load, most of the time. (With a lot of S-facing glazing in very sunny locations it can sometimes underestimate by 5-10% using these methods, but not 25 or 50% unless it was designed as a passive solar house.)

If you're more than 2x oversized, it might be best to just retire the sucker. With a right-sized 80-83% boiler you'd likely use 20% less fuel per year, and with even a bottom of-the-line modulating condensing boiler it would be over 30% savings.

Knowing your altitude may be a factor as well, since we may need to derate the as-used output of the existing boiler above 7000' from it's lower altitude numbers. (If you're at 5K' it's "close enough" but at 10K' it's very significant.)