I have been lurking on the forums for a few weeks but I have a question I was hoping to get some experienced opinions on.

I just purchased a 2400 sq ft 1970's (read-not great insulation) house up at 8500' west of Boulder, CO.  The previous owner installed a Radiantec open-direct system with an electric water heater, supplemented by 6 4x8 solar collectors on the roof.  I want to replace the setup with a closed loop mod/con boiler, leave the water heater and solar hooked up for my domestic hot water for now, and eventually use my solar collectors to feed the space heat and an indirect domestic hot water tank using the boiler as back-up.  I got 2 quotes to install a mod/con with outdoor reset, and new piping/pumps to feed my current system.  It is a staple up with plates (lightweight cheap ones, about 50% coverage) with radiant barrier and r-19 fiberglass underneath it.  Also the tubing is non oxygen barrier.  This only feeds about 800 sq ft of the house, the rest is on a combination of electric baseboard and pellet stove, but will be converted either to a sandwich style radiant heat or radiant panels over the next year or so.  Also the staple up will probably be converted to a sandwich system when i can afford to re-do my floors.

So i guess my question revolves around the two quotes, as they vary in price wildly.

Quote 1:

Install 99k btu munchkin contender using primary/secondary scheme, new SS grundfos pumps, outdoor reset, zone valves, new piping and manifolds.  Labor and parts $6600

Quote 2: 

Install Vitodens WB 6-24 using primary/secondary with a low loss header, re-use my existing SS grundfos that feed my two zones for the primary secondary pipes.  A flat plate heat exchanger and SS gundfos alpha pump to isolate the non oxygen barrier tubing from the boiler, and set it up for constant circulation with TRV's.  Parts = $9800, labor = $6600, total = $16,400.

Both companies will provide for future expansion with an indirect water heater, additional zones, and be able to use my solar panels.  I realize that the second quote has a higher-end boiler and more expensive parts, but the labor charge seems very high.  They claim it will take 2-3 guys a full week to do the install.  The first quote includes a heat loss calc if i provide them with the house details, the second includes a full room by room heat loss calc done by the company.

The problem is I don't have any reference point on what a boiler install of this nature should cost, and if i'm setting myself up for shoddy work if go with the cheaper contractor.  Also there seems to be differing opinions on weather a munchkin needs to be isolated from non oxygen barrier tubing.  I like the idea of constant circulation, but is it worth the extra money?  Also the first company said they have never heard of constant circulation being used with radiant floors. 

Any advice from those that have been there, done that?  Sorry for the book, theres probably even more info I could provide if anyone is interested.

A coupla thoughts...

Curiously both have selected roughly the same size boiler BEFORE doing a heat loss calc. On what basis did either of them pick a boiler size? They could be either over or undersized, depending on derating for altitude and other factors.

If the radiation is already in place and isn't changing right away, what's the point/value of a room-by-room heat loss report until/unless you're ready to lay down the new zones (at which point things may have changed.) A simple whole house heat loss should be good enough for sizing the boiler. If the room-by-room analysis also came with radiant layout for each it'd be worth something, I s'pose, but with above-the-subfloor systems getting the heat into the room wouldn't usually be a hard design problem, and if you're using TRVs & zoning each room separately you don't have to sweat the balance issues.

Are either of these boilers rated to run at 8.5k' of altitude? (Some of the Vitodens documentation says "suitable for use up to 5000'" right on them, but I don't have any specific info about the WB 6-24)

Is the stainless heat exchanger in the Contender less sensitive to non-oxy-barrier tubing issues than the stainless used in the Vitodens? Beats me. Might be. But the extra cost of an isolating heat exchanger should be under a grand, installed.

For a simple boiler swap with few system modifications the Contender quote isn't outrageous, but the question remains as to whether more extensive modifications need to be made, but figure it's a ~$2200-2500 boiler with another $1000-1500 of other parts plus $2-3K in labor tacked on to come up with $6.6K

The labor part other quote feels a bit fat for me, but not having installed one... still, 1/2- 3/4 of a man-month seems excessive. I can't quite figure how it's more than twice the labor of the Contender installation.

~200 square feet of solar collector seems like a heluva lot just for domestic hot water unless you have a high shading factor or lottsa peops living there. I presume you already have heat dumping figured out?

Constant flow might be nice, but isn't really necessary. It'd save you from hearing the tick of the pex moving in the thin plates, but won't dramatically affect comfort. It may affect efficiency somewhat if you've micro-zoned the place to death, as a way to keep the boiler from short-cycling on the smaller zones. If the smallest zone is 1/3 of the house it's effect won't be measurable, but if every room is it's separate zone, it can be. A central buffer set up as your primary/secondary hydraulic separator with an ECM pump + zone valves or separate zone circulators for the zones can often achieve similar (or better) efficiency. But that's a system design nit to pick, and costs of different approaches would have to be analyzed. If it's a 2 zone system (with no tiny zones) neither TRVs nor buffering schemes would buy you very much if the boiler is right-sized for the whole house load.

Get references for both contractors, preferably from people who live at your altitude (or higher.)

Thanks for the response Dana.

I believe the boilers were sized according to "experience", but I won't let any contractor sell me on a boiler size without a heat load calculation.

I figured the room by room heat loss will be useful as I plan on laying down new in floor radiant or radiant panels in the other parts of the house (heated by baseboard electric and one area a pellet stove) within the next year or so.  I'm not sure if it comes with a tubing layout design or not, a good question to ask.

Viessmann's website claims the Vitodens is good for 10,000 ft, I didn't see anything elevation specific when reading about the munchkin, but I do know my neighbors are running one.  Also Viessmann specifically says that non barrier systems must be isolated with a heat exchanger, once again I didn't see any mention of it in the munchkin literature.  Since I am running an open system currently and I have extremely hard water, I feel like it would be a good idea to isolate the existing system from the boiler regardless to minimize the chance of any mineral buildup already in the tubing from clogging up my boiler.

Without having an real experience in this area, the munchkin quote seems fair to me, and the Viessmann seems high, parts aside.  But I don't have any reference points so I don't know if the munchkin is way low which could result in bad work and lots of extra cost tacked on, or the viessmann quote is just a rip off.  I would think a boiler install is about a 3 day job, but i dont know.

You would be correct on the collector size.  Overheating isn't an issue right now as any energy from the panels is promptly being put into the house.  When the boiler is installed and the panels only feed the domestic hot water, i will have to get up there and cover a few of them up with a tarp.  This is of course a temporary solution as I plan to put in a large water storage tank and proper heat dump, but the boiler is at the top of my list at the moment.

The house is only a 2 zone system now, but with the next year or so, it will grow to a about 6 zones (2 zones for downstairs, 1 zone feeding radiant panels w/ trv's upstairs, 1 zone in bedroom/office, 2 glycol zones feeding the greenhouse and detached studio).  It seems like the contender system could be converted to run constant circulation by using trv's instead of zone valves and an ECM pump.

Also, I am still trying to figure out what advantage (other then quality) there is to using a Munchkin Contender, Vitodens 200, or a Triangle Tube Prestige.  I believe the Vitodens has the outdoor reset built in, plus a few setback features, but what else?  Also, does one boiler afford more versatility or control when I go to integrate solar hot water into my space heat?

trevor

They warn against "continual fresh make up water" on page 3 of the Contender user manual, so I'd bring that to the attention of the contractor if you're continuing to run the radiation side as an open system- it needs to be isolated. (Whether open systems are ever a good idea is another can o' worms.)

Depending on how the solar storage is plumbed, it might be impressed into service as buffer for the heating, but that may add unnecessary complexity to the system.  Is THAT the hot water heater that also supplied the 800sf of radiant?

The Triangle Tube boilers get rave reviews from installers & users (and also have integrated outdoor reset.)

Contenders without Vision controllesr still have a tweakable curves that can probably be tuned reasonably (and re-tweaked seasonally, if you want to get the last 2% out of it), but if you intend to also run an indirect you'll probably do better with the more sophisticated controls.

ECM & TRV can be made to work with any boiler- whether it buys you any efficiency is a function of the system design. (But since it sounds like you're micro-zoning, taking some measures is in order.)

The overall efficiency of any of them is affected by

A: Return water temp (at 8.5k' you need to be at 110F or lower to get much in the way of a condensing boost, whereas at sea level you start doing pretty well at 120F.)

B: How low is it's lowest modulation (which affects how many fixed cycling losses you're throwing away under part-load.)

Outdoor reset helps a lot for optimizing A, but does nothing for B.

Issue B. is also very important when microzoning.  Without buffers, situations will occur where most of the TRVs will turn down, the heat has no place to land and it will short cycle. But the lower the min-mod, the less often this occurs.  Designing it with SOME amount of thermal mass to prevent those losses is usually a good idea.  Most of the season you'll be well below the peak heat load requirements, and most of these only have ~1:4 turn down ratios. With slabs the thermal mass is built into the radiation, but in staple-ups and sandwich designs, not-so-much.

Many/most boilers require custom kits to make them run properly at high altitude- it's not precisely the same unit that runs at 2000' or lower, and it's output will be less up in that cheap low-rent alpine air that doesn't come with much oxygen in it. ;-)  Hopefully the contractors have a handle on what it takes to make 'em work right, and how much to derate the output for altitude when picking the size. Pick their brains on the subject a bit, see what falls out.

The radiant side will no longer be an open system, basically the radiant will be run as a conventional closed system, and the electric water heater and solar panels will be left to handle the domestic hot water. In the future the solar will be tied back into the space heat with a large water storage tank, and the domestic hot water will be supplied using an indirect tank from the boiler.

As the system sits, I have an 80 gal electric water heater with a solar heat exchanger. The water heater (set at 130 deg F) feeds both the domestic hot water and the 800 sq ft radiant system. To call it a rig job would be giving it too much credit, and it does an inadequate (yet expensive) job of keeping the house warm. This was especially evident a few months ago in december when it was -12 deg F and we had 50 mph winds, i would wake up to a house at 52 deg, cold!

When you say i will probably be better off with more sophisticated controls, do you mean the TT would have more sophisticated controls then the Munchkin? I have no problem buying as nice of a boiler as I can afford, just as long as I am getting some added benefit from a step up in price. Although for now the boiler will just be running an outdoor reset, I want the future integration of my solar to be as simple as possible. So I guess if a triangle tube or viessmann has more flexibility for my future plans it would be worth spending the extra money. Does anyone know that out of a viessmann, TT, or munchkin which would lend itself better to integrating solar hot water into my space heat?

There wont be any thermal mass in the system, so I will have to make sure the contractor sizes the boiler correctly, and that may be an issue with TRV's. I will also ask lots of questions about their experience with installing boilers at high altitude. Thanks Dana for all the help you have given me. I guess I just need to pick the contractor's brains a bit more. I am still wondering why there is such a huge gap between labor prices for the boiler install. Does anyone have any experience to say one is way high or way low?

The distinctions between 95% high efficiency condensing boilers are subtle and mostly reserved to the few who have actually installed them, or been to a factory certification training (any one will due).

All three boilers have outdoor reset "built-in". The TT and Munchkin controls are comparable. The Vitodens is a bit more sophisticated with night setback, integral ECM circulator (which one can use as system pump) no mandatory primary/secondary. These extras are of little consequence if the installer leaves the outdoor sensor in the box or fails to change the factory setting to reflect your particular climate.

Near piping and load balancing can mess up the best installation.

Residential boiler systems should be charged with soft water, open systems are silly and will certainly void all manufacturers warranty (DIY installation will have the same results BTW).

Computer generated Manual 'J' heat load analysis is a must and room-by-room analysis is needed to specify a radiant floor panel of any kind.

Posted By milo902 on 17 Feb 2010 07:29 PM
The radiant side will no longer be an open system, basically the radiant will be run as a conventional closed system, and the electric water heater and solar panels will be left to handle the domestic hot water. In the future the solar will be tied back into the space heat with a large water storage tank, and the domestic hot water will be supplied using an indirect tank from the boiler.

As the system sits, I have an 80 gal electric water heater with a solar heat exchanger. The water heater (set at 130 deg F) feeds both the domestic hot water and the 800 sq ft radiant system. To call it a rig job would be giving it too much credit, and it does an inadequate (yet expensive) job of keeping the house warm. This was especially evident a few months ago in december when it was -12 deg F and we had 50 mph winds, i would wake up to a house at 52 deg, cold!

When you say i will probably be better off with more sophisticated controls, do you mean the TT would have more sophisticated controls then the Munchkin? I have no problem buying as nice of a boiler as I can afford, just as long as I am getting some added benefit from a step up in price. Although for now the boiler will just be running an outdoor reset, I want the future integration of my solar to be as simple as possible. So I guess if a triangle tube or viessmann has more flexibility for my future plans it would be worth spending the extra money. Does anyone know that out of a viessmann, TT, or munchkin which would lend itself better to integrating solar hot water into my space heat?

There wont be any thermal mass in the system, so I will have to make sure the contractor sizes the boiler correctly, and that may be an issue with TRV's. I will also ask lots of questions about their experience with installing boilers at high altitude. Thanks Dana for all the help you have given me. I guess I just need to pick the contractor's brains a bit more. I am still wondering why there is such a huge gap between labor prices for the boiler install. Does anyone have any experience to say one is way high or way low?

By "more sophisticated contros" meant that the bare-bones Contender controls aren't as fully-featured as when coupled their Vision series controls (which are designed specifically for the Contender.)  IIRC the dumbest Contenders don't use a true outdoor reset, but do heat-load sensing via the system response, which can be "as-good-as", when properly adjusted.  The Vision controls all have true outdoor reset, heat-purge functions, boiler control of indirect hysteresis, can run different zones at different temps, have programmable priority zoning, etc.  They plug right into the Contender.  (But I've never used or set up a Contender with or without a Vision controller- I'd defer to the experts on the details.)

No boiler is more or less appropriate for integrating with solar- that's a system design issue.

Even if it's nothing more than a 30 gallon electric tank (not wired- just using it as a  tank) in series with the boiler's output it'll be able to keep the system from short-cycling during part load.  It may/may-not be the ideal way to buffer the system, but microzoning without a buffer of any kind is a recipe for multiplying the number of burn cycles, reducing boiler life and system efficiency.  But "design by web-forum" is a lousy way to go.  It could well be that the extra few grand in "labor" for the higher-priced quote actually falls under "system design", since yours isn't just another 1-2 zone boiler swap kind of setup.  I'm still a bit skeptical about their willingness to spec a boiler size before doing the heat loss analysis though.

If the electric tank was the sole source of heat during those bitter nights, knowing the wattage of it's heating elements and both the indoor & outdoor temps would probably get you pretty close to the true whole-house heat loss.   (X) kilowatts results in a delta-T of 52F + 12F= 64F, from which you can caluculate how many kilowatts it would take to get the desired delta-T on design day.  If your outdoor design temp is say, -20F, and you need it to be 68F inside, that's and 88F delta-T that you need to support, and the kilowatts will scale linearly. The boilers they both specified will deliver ~22-26kilowatts of output at sea level (don't know how they derate for your altitude.  If the pellet stove/other was supplying any portion of the the heat you can't get there from here though.

I am not that for from you and a bit higher.

Just my thoughts

I think you should look at the storage/heat exchanger as being the heart of your system especially as you have mutiple heat sources.

You can feed this from you Solar panels and use the gas to provide backup, my guess is that your solar should provide a lot of your heat for summer/shoulder seasons. A big enough tank would really help minimise your demand from other systems.

I do not know about the Boilers you mention, I know that our Rinnai was good to go at nearly 10,000. Obviously we lose a lot of output.

This should be a separate thread but I had one installer who sent me calculations showing the propane usage stayed the same even though the output decreased.

I forgot to mention, you mention pellets and I assume you have access to wood, that gives you also the option of adding Biomass later.

I don't live in Boulder, but I live in the mountains...

I have a few quotes for replacing my closed system copper finned boiler/indirect hot water heater with a Mod/con & new water heater...

I have been told its a 2-3 day job to a 5 day job.

I have quotes of 16.5 to 17k.

Lets just say that I would be hard pressed to come up with over 7.5k in materials...  Very hard pressed, and that is just googling the parts..

The quote that I have that breaks out materials vs labor has over 13k in materials listed...

I have no problem paying a fair price for materials (30% or so above wholesale maybe?)  + a fair hourly wage (100-125$) an hour...  But I can tell you that the few that I have talked to are WAY over priced...

Seriously over if I have a wholesale quote and the one fellow DOUBLED the wholesale quote...

Boulder is an expensive place to live.

But I doubt that the contractors on the front range are hurting less than from where I am.

I know many who would grab $100 an hour all the way to the bank.

Sounds like you need to shop around a bit more.

Who? I am in Leadville

Leadville is another issue. I guess you are looking to Salida or Summit for contractors?

You have the same HDD as we do.

I know a lot of the Springs contractors do work in Summit, abcplumbing for example.

I have had people from New Castle to Summit to Buena Vista...

I am probably going to do it myself..

I want to be treated fairly. Fair markup on parts/fair wage...

I feel like I am being taken advantage of at 80-100% markup on parts..

For instance:

Boiler wholesale $3300 Contractor to me $5155
Pumps wholesale $500 Contractor to me $1500
Copper/Valves/Gauges Contractor to me$3600 
Exhaust wholesale $600 Contractor to me $1400


Total parts to me $13,855   (wholesale I estimate$7k at most)

AND $2880 in labor

I would go back to them and say that you will be providing the equipment.

Don't know if they will take me up on that offer... 

Just seems ridiculous to mark up stuff that much..

chtucker,

Where do you find the wholesale prices at for comparison? My high bid came in at about 9.8k materials 6.6k labor. I checked a few of the big ticket items (boiler, vent kit, pumps) and they were charging me the same amount or less then I could find it online. I don't have access to any information regarding wholesale prices, but I dont see any reason a contractor should be charging you significantly more then retail prices, as they are getting them at wholesale prices.

I realized after going through the cheaper bid they might have misunderstood what exactly I wanted to do, as they left off manifolds and zone valves. I also get the feeling that they are the type of contractor that simply installs standard setups, and not much design goes into it. As I tend to obsess a bit over efficiency, if I am going to pay someone to install a system for me, I personally want some time spent on design. This unfortunately means I may have to bite the bullet and pay the more expensive contractor in order to make sure my system is not on installed correctly, but designed correctly as well.

I called up the regional wholesaler in Durango and asked for pricing.  I have a written quote on equipment.  As for the pumps, they were found online at multiple sources. 

I also looked at the Boiler manufacturer's MSRP price list...  and the boiler itself is priced at $3855 RETAIL...

I don't expect to pay $5155 for something that the MSRP is $3855...

if you want to send me you email address, or call me for that matter, I can forward what I have..

mtnbronco at gmail.com