Chimney vs. Direct Vent vs Power Vent for oil boiler

[thomase00]

I have some updates.

So far, I have the following estimates, NONE of which are itemized. Also, keep in mind that I want to direct vent about 25' away from the current boiler location.

1.) From my current fuel oil supplier whom recently started a propane business in the last few years. This is the guy I mentioned before who wants to put in an over-sized Bosch Greenstar 131, BUT he'll do EVERYTHING, including burying a 500 gallon tank, fixing my lawn, removing my oil tank, and locking me in for $1.79 propane for a year, all for $5600! Assuming I could convince him that I only need a Greenstar 100 or Greenstar 79, this is SOO much cheaper than everyone else (about 1/2), it seems that something isn't quite right. Maybe he's trying to build up his propane customer base and is willing to do it for near cost. Maybe he's planning on jacking up the propane price after the 1st year. It is very tempting but also concerning.

2.) The fuel oil branch of the same company from 1.) quoted me about $10K for a power-vented Weil-Mclain WGO-4RD (!) moved across the basement and vented out the leeward side basement wall. Even a WGO-3Rd would be oversized. I didn't push them to explain why it needed to be so big because this was very early on before I came to this thread and did my own heat loss calculation.

3.) Another company that sells both propane and fuel oil quoted me about $10K for a direct vented Peerless WBV-03, and $12K for a Dunkirk Helix VLT 100. Coring through the basement wall (needed for both) runs another $500 and installing the tank and running the propane gas line runs another $700.

4.) Independent plumber and heating contractor quoted me $10.2K for a Buderus g115ws/3 and $11K for a Bosch Greenstar 100 (similar to the 1st guy but double the cost). This doesn't include an EXTRA $3k (!) if I want it moved near the leeward side basement wall. Logamatic 2107 for the oil boiler is another $1k, but he doesn't recommend it because he says customers don't like losing the ability to crank the thermostat up and down at will. This guy said he would charge for a thorough Manual-J, but I showed him my own report and he said it looked reasonable.

5.) A different full service heating company that delivers oil (but not propane) quoted $10.9K for a Buderus g115ws/3 moved to the other side of the basement with direct vent cored through the foundation. He also doesn't recommend the Logamatic for the same reasons as 4.), so his installation instead includes a different outdoor reset control (maybe the Tekmar 260?). He will add the Logamatic for another $900.

However, 5.) ALSO quoted $10.4K for EK 90+ Resolute which he says can be vented up to 50' with EK's polypropylene venting system (even for oil), which means the system can remain in the same location of the basement. I'm not sure if there are downsides to using my current Mega-Stor indirect with EK's system. It seems like he is pushing more for the EK system.

It is frustrating that no one is giving me an itemized estimate. I can ask, but its not like that is going to change the total.

Finally, all of these estimates seem to be significantly more than what friends and family have paid in the last few years. None of this includes MassSave rebates that I will get back ($1700 for oil and $1500 for propane), and only 5.) was aggressive about guiding me through the rebate process. 3.) mentioned that I should qualify for a rebate, but left it at that. 1.)/2.) doesn't seem to know much about the rebate process at all.

 

[Dana]

1>It's the guaranteed low first-year's (sometimes only first-tank's) price and low installed price that get's people to switch to propane, but they usually end up paying a for it later.

Also the proposed boiler has a ridiculously high 36,000 BTU/hr minimum fire input (practically your entire design day heat load!) , and you don't have anywhere NEAR enough fin-tube to run it in condensing mode! There's no point to a modulating boiler that only modulates when it's colder than 15F outside, and no point to a condensing boiler hooked up to radiation where it can't run at a condensing temperature without short-cycling itself into an early grave.

Seriously, this is the WORST proposal up there, at any installed price!

Even the Greenstar 79 is a lousy fit for your radiation, since it's minimum firing rate is 23,900 BTU/hr in, 22,700 BTU/hr out (more than half your design condition load). Even at minimum fire it needs at least 110' of baseboard per zone to operate at 95% efficiency without cycling. With just the 72' zone at 130F AWT (the beginning of condensing) the radiation is only emitting ~18,000 BTU/hr, so with the "extra" 4700 BTU/hr of burner input and very little thermal mass to work with temperature is going to be slewing more than 10F per minute, and it'll be short cycling, averaging under 90% combustion efficiency, and losing even more to the flue purges and ignition cycles.

With their low turndown ratios and high minimum firing rates the Bosch Greenstar series works better when retrofitted onto systems with big high-volume radiators (where it has some thermal mass to work with), and not low mass fin tube baseboard unless you have a LOT of baseboard on each zone.

2>The WTO-2 is a ~$1500 boiler, compared to ~$2000 for the WTO-4. You'd save a bit up front by right-sizing it if you went that way, but it's still pretty low end for the money.

3> The Peerless WBV-03 with the commonly shipped burners is oversized for your load, but with a Riello F-3 burner it can be down-fired to 0.60 gph, which isn' t terrible. A propane fired Dunkirk Helix VLT 100 propane mod-con is also way oversized for your load, with a high 20K-in/19K out minimum fire. It would just barely make it into the 90s for combustion efficiency without short cycling and you'd have to tweak it to find that fine edge. (The Helix VLT 50 would be about right, but they didn't propose that.)

4>The minimum firing rate on the Bosch Greenstar 100 is 24,600 BTU/hr in, 23,370 BTU/hr out (in condensing mode.) That's more than half your heat load, and would require a minimum of ~115' of baseboard per zone to be able to run in condensing mode without cycling. It'll short cycle like crazy with just 62' or 72' zone calling for heat. Definitely a crummy choice for you, as are any of the Greenstars series (as noted in 1>)

5> Outdoor reset without heat purge control increase rather than reducing the number of burn cycles. It buys some comfort, but not efficiency.

However 5> The EK 90+ (fitted with the 0.68 gpm nozzle, or even the 0.74 gpm, not that you need it) is clearly the best proposal up there. The heat purge control is more sophisticated than most retrofits, and makes use of the thermal mass of the indirect. Whether it would work exactly the same with your existing indirect or not isn't clear.

While it's frustrating, most quotes will never be itemized, since it invited nickel & dime negotiation over every last line item, and just eats up time. Nobody can really afford the time (or psychic energy) to do that over and over again with every last proposal.

 

[Sponsor]

 

[thomase00]

It bothers me that the low priced quote is such an outlier. I actually talked to him again and he flat out refused to install anything with less capacity than the maximum output of all my baseboard plus 20K extra for the indirect. He keeps boasting about how large his business is, how long he has been doing this (35 years), how I can't go wrong going with him, and how pleased I will be with the results. I think it's a little weird that the owner of the company would be out doing estimates, but he'd claim it's a testament to his customer service.

Maybe over his 35 years of experience, he's learned that customers never complain when the thermostat is satisfied instantly. He insists that the baseboard IS the load and that a heat loss calculation is pointless once the baseboard is already there.

Are there really installers like this out there? After all, this is a full service company that sells fuel and service contracts. I have little doubt that they have thousands of heating oil customers, and are installing 100s of systems per year.

I feel like I'm being gaslighted (no pun intended).

 

[thomase00]

The EK system is tempting, but I've heard mixed reviews regarding maintenance costs and the company itself. I'll get a 5 year parts and labor warranty, but I'm concerned that I'll be rolling the dice after that.

Apparently, they are unlike ANY other manufacturer in that they don't share pricing information transparently with installers/servicers, sell all parts direct to installers/servicers instead of through supply houses (unlike every other manufacturer), require that all installers PAY to attend "training" at the NJ headquarters (which is actually sounds more like some kind of cult-like multi-level-marketing sales/marketing convention).

Regarding the Buderus system, I understand that outdoor reset won't necessarily reduce cycles (may even increase), but I thought there is efficiency to be gained by lowering the max boiler temperature? I wouldn't be surprised if a 150F baseboard temp satisfies my design day heat loss. What about arguments for/against the Logamatic?

 

[thomase00]

I found out that the proposed non-Logamatic control for the Buderus is the Hydrolevel 3250. This sounds similar to the Intellicon control but it has an optional outdoor reset which can be used instead of the "thermal targeting" feature. It also has a thermal pre-purge feature where it will attempt to predict if a call can be satisfied with latent heat in order to avoid turning on the burner. It does this by monitoring the rate of change of boiler temperature, but I'm not sure how that is useful. Don't you need feedback from the room? Seems like it would be better to monitor the rate of change of room temperature directly. Thermostats should transmit actual temperature information to the boiler control rather than simply on/off!

You say that outdoor reset helps comfort but not efficiency. How so? Doesn't lowering boiler temperature gain efficiency?

 

[Jadnashua]

A properly sized and setup modulating system would be optimized to run constantly at just the right temperature to replace any heat lost to the outside. In theory, knowing the outside temperature can help the boiler decide what temperature is needed to obtain that, but a lot of it can be inferred by monitoring the outlet and inlet temperatures to the boiler. But, most modulating boilers do not have enough output range to enable it to do that except when the load is higher (i.e., it's colder out there or really windy). On a mild day, you may be very comfortable with the water barely 120-degrees or maybe even less (if the boiler is designed for this low of a temp). The radiation rate varies more with baseboard than something like say a heavy CI radiator, so it's not linear. That's where programming and adapting the curves for your system comes in.

It's sad that there are a lot of installers that either don't understand how to make an efficient, long-lasting system or are too lazy to do the legwork to figure out the best result. It is far too common to oversize things. They never have to get a complaint that the house is cold, but the comfort, efficiency, and longevity of the system may suffer.

Adding 20K BTU for the indirect is totally unnecessary unless you're running something like a laundromat or spa and were using hot water in huge volumes throughout the day. Modern practice calls for making the indirect a priority zone, where it gets 100% of the boiler's output when needed. This typically very quickly reheats the thing, and then the house can get its normal flow back before anyone notices - how many days is the boiler running 100% duty cycle and just barely able to keep up? You've probably never run into that situation. The other thing that isn't always clear...say you've sized the boiler for that 99% day, and it hits 100% - slightly more heat leaking than can be replaced...the house doesn't magically turn into an icebox...instead of being able to hold 70-degrees, it might drop to 69. The issue you might have is if you setback things, without some excess, it can take a long time to recover. I've never felt the house cooling off as the result of using lots of hot water and mine is plumbed as a priority zone.

 

[Dana]

Seriously, the low-bid guy who adds 20K for the indirect may have been doing it for 35 years, but he's a hack- an old dog incapable of doing even the most rudimentary lipstick-on-mirror math, let alone learning new tricks!

The Bosch Greenstar 131 combi-boiler is really marginal as a hot water heater at your wintertime incoming water temps. It'll support one full-flow shower, but without a lot of margin. It's minimum-fire output is high enough to have flame-out and poor temperature control issues in hot water heating mode in the summer. The minimum fire output is also well over half your design temperature heat load, so it'll almost never modulate, and the min-fire output is too high to run at condensing efficiency. That's three strikes: Marginal (at best) domestic hot water delivery, a min-fire so high it can't modulate, and a min-fire to high to even condense without short cycling.

The fourth strike is that after year 1 propane won't be $1.79 any more, and you'll be stuck paying whatever this guy will charge, since it's a mini-monopoly- he'll own the tank, and the exclusive right to filling it. There is no "maybe" about it- he's quoting you roughly the raw material cost of the tank & combi boiler & associated hardware, and he's not running a charity. It's going to cost HIM more to install the buried tank & boiler than he's quoting. He will HAVE to charge you a premium on fuel down the road to pay off his sunk costs. And given what it costs to dig up and remove a buried tank full of flammable volatile liquid, you can bet the cost of changing fuel suppliers is going to be excruciatingly steep.

Outdoor reset with non-modulating boilers increases the number of burn cycles, since it restricts the high-limit, and there is a low-limit below which you can't go with an oil boiler without destroying the boiler with corrosive exhaust condensation on the heat exchanger plates. That's typically ~130-135F, but most manufacturer's specify a low-limit of 140F for the return water temperature to have some margin. Even at 140F excessive flue condensation becomes an issue for atmospheric drafted oil boilers, which is why only stainless flue liners can be used. Most of the time you don't even need 140F for an OUTPUT temperature to be able to heat the place, which makes outdoor reset less useful than with gas boilers (which can be run as low as 130F without creating problems) or condensing boilers, which can be run at arbitrarily low temperatures (as long as it's above freezing. ) So with outdoor reset on an oil boiler it ends up limiting the high temp, which means more lower distribution & standby losses, but much higher numbers of burns, incurring a loss with each ignition cycle.

Smart boiler controls such as the Hydrolevel 3250 or Intellicon "learn" your system, differentiating zones by the delta-Ts, and the outdoor temperature by how rapidly the thermostat is satisfied, and learn to anticipate the end of a call for heat, cutting the burner early, and letting it finish by purging heat from the boiler. Then on new calls for heat it continues to purge heat from the boiler into the zone, not firing the burner until the programmed low-limit boiler temperature is reached. That lowers the average temperature of the boiler between calls for heat, which reduces standby & distribution losses, and lowers the total number of burns, for lower ignition-cycle losses. They are in many ways comparable to the heat purging functions of the System 2000 or EK90+.

A properly installed System 2000 or EK90+ should last as long or longer than any cast iron boiler. Steel is more flexible, making it more tolerant of thermal cycling than cast iron, making Energy Kinetics and other steel boilers less prone to cracks & leaks. The System 2K series has a pretty good reputation, but I haven't heard much either way on the EK90+. (Sometimes with very high efficiency oil boilers the quality of the fuel becomes more important, especially at smaller nozzle sizes.)

 

[thomase00]

I'm leaning heavily toward the EK 90+ particularly because the Smart Vent supports long runs, eliminating the need (and associated expense) of moving the whole setup across the basement.

Assuming I go that way, the remaining question is whether I should keep my existing indirect or "upgrade" to EK's integrated DHW system. There is a really interesting thread over at heating help.com where to EK owner responded to a bunch of my questions regarding EK's DHW system. My installer recommends keeping my existing Megastor and switching to EK's system when it needs to be replaced. I think the additional cost to switch to EK' DHW would be about $1400.

https://forum.heatinghelp.com/discussion/comment/1476699#Comment_1476699

Another question regarding the EK is that the minimum nozzle size is 0.68, which will result in more oversizing than a Buderus with a 0.6 or 0.5 nozzle. I keep hearing about how bad short cycling is, so I'm curious as to why this potential negative isn't mentioned in the context of the EK system.

 

[Dana]

Even though 0.68 gph is oversized for your heat load, it's not super- oversized for your zone radiation, especially with heat purge controls limiting the numbers of burn cycles. Even with just the 62' zone calling for heat it'll cycle at about a 60% on/40% off duty cycle, but the smart controls will make maximal use of whatever thermal mass there is in the boiler + zone to maximize burn times, and purge any boiler heat left over at the end of a call for heat into the indirect, parking the boiler at a lower temperature than some heat purging smart-controllers. With a ~60% duty cycle the odds of overlapping calls for heat from another zone go up too. With the 72' baseboard + toekick zone calling for heat at the same time as the 62' baseboard zone it will run pretty much continuously until one of the thermostats is satisfied.

I don't think there is anything too special about their indirect. If it saves you over a grand up front and the installer is on board with it, go for it! Indirect water heaters usually last well beyond the warranty periods, so you could easily have another decade to save up for gray EK indirect with canary yellow printing on it.

 

[thomase00]

It seems like EK's indirect is more effective at purging the heat out of the boiler at the end of the cycle. It is similar to a aqua booster setup (as opposed to an indirect), except that rather than using a boiler's internal tankless coil, there is a "zone" (like an indirect) which circulates boiler water through an external flat plate heat exchanger. On the DHW side, water is recirculated (like an aqua booster setup) through a loop going through the other side of the heat exchanger. This system always pulls from the coldest water at the bottom of the DHW tank

 

[Dana]

It's more effective, but not necessarily $1400 more cost-effective on the additional efficiency over the remaining lifespan of your existing indirect. The lower you set the aquastat temp on your indirect, the more heat-purge efficiency you'll get out of it.

An aquastat setting of 140F is code for new water heater installations, but 120F is enough to keep legionella colonies from growing, and, and it's likely that heat-purging the boiler will take it up to 140F or higher from time to time. (140F is enough to eventually kill off legionella, but not instantly.)

 

[thomase00]

I've been thinking...

Is it really that important to minimize heat left over in the boiler if it would otherwise radiate out into the basement which is within the thermal envelope of the building? If not, any efficiency gains from an EK system during the heating season are not really coming from minimizing left over heat so much as from minimizing burn cycles as you described above. If that is the case, how much reduction in fuel usage can I realistically expect? I wouldn't be surprised if those big "potential" savings (40% or more) are for systems where the boiler is in an unheated garage or something similar.

On the other hand, I understand that minimizing left over boiler heat has value in the summer when I'm only producing DHW and the extra heat dumped into the building needs to be "removed" by the AC, but summer DHW accounts for only a fraction of my annual oil BTUs (maybe 10%).

 

[Dana]

AFUE testing presumes the boiler is inside of conditioned space, so something that tests at 90% AFUE really WILL do better than something that tests at 86%.

Oversized boilers typically overheat the basement, which raises the actual load due to the higher indoor temperature. This effect is pretty severe in basements where there is no foundation insulation, since the heat loss through the ~R1 of uninsulated above-grade foundation is 1o x that of a 2x4/R13 framed wall per square foot. Lowering an uninsulated basement's temp from say, 68-72F to 60-62F is a huge improvement, since the heat flux out the basement walls is dramatically lower. In a tight fully insulated basement there's still a measurable improvement, but it's not as striking.

Three pages into it I can't remember any more if you've ever described the air tightness and insulation levels of the basement.

 

[tmac0]

May I ask what your result was? Did you learn more about direct venting and go that route? I have a somewhat similar situation with possibly direct venting a new oil furnace versus continuing to use a chimney that's far away. I'm interested in any update. Thanks!