Replacing FHW boiler - what to choose????
#1
05-02-07, 10:53 AM
Replacing FHW boiler - what to choose????
Current boiler - Burnham V73 - is dying and needs replacement. Thought about going DV so that I could reclaim the chimney for the wood stove, but given that it would be a higher cost for the boiler setup and involve moving an oil tank and full plus trying to find a new home for the propane tank it seems I'm better off sticking with chimney and using the money to add some baseboard.
Used HE2 and came out to 55K to 65KBTU/hr heat loss. I will be able to upgrade the baseboard to about 45KBTU output on ground floor. Second floor has none so it'd involve quite a bit of work to get baseboard online there. Other suggestions?
Now the question is what boiler to choose? I can get a rebate from Burnham, so I was thinking the V83 @ 79KBTU/hr NET, or the LE @ 64K net. Other choice would be a Biasi B10-3 @ 58K, or B10-4 @ 91K. Any others I should consider?
I'm lost on the AFUE ratings and how much they mean in the real world. If I go just by those I might as well choose the cheapest boiler from the pack since all have reported AFUEs of 86% to 88%
Used HE2 and came out to 55K to 65KBTU/hr heat loss. I will be able to upgrade the baseboard to about 45KBTU output on ground floor. Second floor has none so it'd involve quite a bit of work to get baseboard online there. Other suggestions?
Now the question is what boiler to choose? I can get a rebate from Burnham, so I was thinking the V83 @ 79KBTU/hr NET, or the LE @ 64K net. Other choice would be a Biasi B10-3 @ 58K, or B10-4 @ 91K. Any others I should consider?
I'm lost on the AFUE ratings and how much they mean in the real world. If I go just by those I might as well choose the cheapest boiler from the pack since all have reported AFUEs of 86% to 88%
#2
05-02-07, 11:35 AM
How much of a rebate do you get for a Burnham?
As far as matching heat loads to boiler rating the small Biasi seems like a nice fit. From what I've seen and heard they are a sweet little 3 pass boiler that gets to temp quickly.
Hard to comment on the second floor other than maybe suggest Biasi panels piped using PEX-Al-PEX to a manifold that is zoned. You could TRV them all (now or later -- except the one near the t-stat for the upstairs zone). The panels are nice in that you could homerun the supply and return for each panel together to simplify your piping runs. The supply and return fittings on those panels are side by side.
As far as matching heat loads to boiler rating the small Biasi seems like a nice fit. From what I've seen and heard they are a sweet little 3 pass boiler that gets to temp quickly.
Hard to comment on the second floor other than maybe suggest Biasi panels piped using PEX-Al-PEX to a manifold that is zoned. You could TRV them all (now or later -- except the one near the t-stat for the upstairs zone). The panels are nice in that you could homerun the supply and return for each panel together to simplify your piping runs. The supply and return fittings on those panels are side by side.
#3
05-02-07, 03:43 PM
I think it's around $500 for the rebate. I've actually just been recommended against using the smallest Biasi - something about the nozzle gumming up too easy with this low a firing rate. So I'd have to use at least the 91KBTU. If I end up around 60KBTU output, how much running efficiency would I be sacrificing?
for the upstairs zone I can go baseboard. Ceiling is open beam, so it would only require drilling a couple holes and running PEX or copper. Guess PEX would be a lot cheaper although possibly uglier since it'd be exposed.
Now, I'm also being recommended going indirect hot water, which I think would add a good $1K to the cost. Is it worth it as opposed to going with a two year old electric I have kicking around? We have very low HW consumption.
for the upstairs zone I can go baseboard. Ceiling is open beam, so it would only require drilling a couple holes and running PEX or copper. Guess PEX would be a lot cheaper although possibly uglier since it'd be exposed.
Now, I'm also being recommended going indirect hot water, which I think would add a good $1K to the cost. Is it worth it as opposed to going with a two year old electric I have kicking around? We have very low HW consumption.
#4
05-02-07, 05:46 PM
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Boiler
Since you can get a rebate from Burnham, here's one to look at:
http://www.burnham.com/mpo_boiler.htm
In the long run, I think the indirect would be the way to go for your domestic.
http://www.burnham.com/mpo_boiler.htm
In the long run, I think the indirect would be the way to go for your domestic.
#5
05-02-07, 06:53 PM
The indirect is just a money issue. I can spend it on indirect, or I can spend it on additional baseboard and insulation. I think the second is my current best option.
Both companies I spoke to do not at all recommend Burnham - they're in fact quite dismissive of the brand based on whatever experiences they've had. I am somewhat hesitant to ask for it, since I have no way of comparing the different quotes - I have no clue on the base cost of the boilers and people just don't seem to do itemized quotes :/ Not saying the guys are out to get me, but I do like to be somewhat informed.
Both companies I spoke to do not at all recommend Burnham - they're in fact quite dismissive of the brand based on whatever experiences they've had. I am somewhat hesitant to ask for it, since I have no way of comparing the different quotes - I have no clue on the base cost of the boilers and people just don't seem to do itemized quotes :/ Not saying the guys are out to get me, but I do like to be somewhat informed.
#7
05-02-07, 07:20 PM
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Boiler/Indirect
I have no first hand experience with Pensotti & only know what I have read which in general is good.
I would agree with a fixed amount to spend, it would be better spent on additional baseboard & insulation rather than the indirect. One thing I do suggest is to have the piping off the boiler set up for an indirect so that in the future if you decide to add the indirect, the initial piping is already there. The cost to do it now is WAY less than later.
Itemized quotes are rarely done but some contractors will do one if you insist.
I would agree with a fixed amount to spend, it would be better spent on additional baseboard & insulation rather than the indirect. One thing I do suggest is to have the piping off the boiler set up for an indirect so that in the future if you decide to add the indirect, the initial piping is already there. The cost to do it now is WAY less than later.
Itemized quotes are rarely done but some contractors will do one if you insist.
#8
05-03-07, 05:27 AM
When you say to set it up beforehand, you mean the adding 'manifolds' if you will? Basically set it up so that all you'd need to do is add a circulator and the 3/4" piping?
#9
05-03-07, 09:05 AM
I believe the answer is yes. Definitely get the header/manfolds set up so all you have to do is run a bit of supply/return piping for the indirect. Absolutely worth doing now as opposed to later.
#10
05-03-07, 09:27 AM
"I've actually just been recommended against using the smallest Biasi - something about the nozzle gumming up too easy with this low a firing rate. So I'd have to use at least the 91KBTU."
With which burner? The Riello?
With which burner? The Riello?
#11
05-03-07, 11:50 AM
@WHO
Not sure which burner. This happens to be a guy who does a lot of Biasi installs so I assume he has good experience with them in this environment.
So let's say I go with the 91K net, that would put me 30K+ over needed capacity and 40K+ over a single zone output. I assume this will cause the burner to cycle - my current 120K boiler does 15 mins burn 30 mins circulation cycle - and in effect reduce the AFUE? Am I better off getting a slightly lesser AFUE model that is closer to the needed output, or is it OK to be 30% over?
Not sure which burner. This happens to be a guy who does a lot of Biasi installs so I assume he has good experience with them in this environment.
So let's say I go with the 91K net, that would put me 30K+ over needed capacity and 40K+ over a single zone output. I assume this will cause the burner to cycle - my current 120K boiler does 15 mins burn 30 mins circulation cycle - and in effect reduce the AFUE? Am I better off getting a slightly lesser AFUE model that is closer to the needed output, or is it OK to be 30% over?
#12
05-03-07, 06:14 PM
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Manifold
Yes, install a manifold with pipe stubs, valves, & plugs in the valves. This will make adding the indirect (or any other zone) a simple matter in respect to the near boiler piping.
If you are going to add baseboard to the second floor, you should make it a separate zone with it's own circulator. This usually involves installing a mult-zone switching relay & the cost of a three or four zone relay is not that much more than a two zone. I always install one with at least one more zone than I need to allow for some future expansion & just to have a "spare" in case one zone goes down.
If you are going to add baseboard to the second floor, you should make it a separate zone with it's own circulator. This usually involves installing a mult-zone switching relay & the cost of a three or four zone relay is not that much more than a two zone. I always install one with at least one more zone than I need to allow for some future expansion & just to have a "spare" in case one zone goes down.
#13
05-04-07, 01:40 PM
I was thinking second zone, yes. I'll just have them install a three zone manifold and the start of the piping no matter whether I immediately add the 2nd flr zone or indirect.
Still lost on the choice of boiler. Will running the 91KBTU Biasi really be much less efficient than running a slightly lower efficiency more closely matched (say 65 to 75KBTU) boiler? Can this be partly compensated for using outdoor reset or something like Beckett's heat manager, or does it really not matter all that much on a well-insulated boiler like the Biasi? Should I consider a cold start configuration with a bypass? And should I worry about small a small boiler not being able to provide both heat and HW recovery on a cold day?
Still lost on the choice of boiler. Will running the 91KBTU Biasi really be much less efficient than running a slightly lower efficiency more closely matched (say 65 to 75KBTU) boiler? Can this be partly compensated for using outdoor reset or something like Beckett's heat manager, or does it really not matter all that much on a well-insulated boiler like the Biasi? Should I consider a cold start configuration with a bypass? And should I worry about small a small boiler not being able to provide both heat and HW recovery on a cold day?
#14
05-04-07, 06:16 PM
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Heat Loss vs. Boiler Size
If the indirect is a future possibility, I would certainly consider the larger boiler.
Cold start, particularly with a by-pass is the way to go for energy efficiency & helping to prolong the life of the boiler. Outdoor resets can save a significant amount of energy & increase comfort levels particularly when coupled with constant circulation.
Cold start, particularly with a by-pass is the way to go for energy efficiency & helping to prolong the life of the boiler. Outdoor resets can save a significant amount of energy & increase comfort levels particularly when coupled with constant circulation.
#15
05-04-07, 06:29 PM
I think I'll be going with the Biasi B10-4 then. The only other thing I considered is a low-mass steel boiler to save on standby losses, but if the Biasi will live in cold start environment then there's probably not much sense to that - from what I can tell it's one of the lowest cost high-efficiency boilers even when compared to steel.
Thanks for the help
Thanks for the help
#16
05-04-07, 06:34 PM
I would vote for cold start with a Danfoss thermic bypass, outdoor reset with a tekmar or Taco reset control, and DHW priority on the control. If you're thinking indirect, then you could add an anti-scald mixing valve on the domestic hot and run the indirect at ~140F. This would effectively make the DHW tank larger by decreasing the rate of drawdown. If you're contemplating a 40 gal indirect, then a boiler with a DOE rating of 70-80k should be fine. (I would also add that for sizing for space heating and even the indirect, IMHO the IBR rating, particularly with outdoor reset, is overkill. Use the DOE.)
Of course I'm somewhat biased because I've nearly described my own system, which seems to be performing quite nicely.
I absolutely cannot say enough good about outdoor reset and near-constant circulation. It has completely changed not only our fuel use but also the thermal characteristics of the house. This house is full of fin-tube baseboard. The house just IS the set temp. Set back a couple degrees for sleeping; takes a few hours to recover, but otherwise no fluctuations. Just nice, mellow, constant heat. Great stuff.
Of course I'm somewhat biased because I've nearly described my own system, which seems to be performing quite nicely.
I absolutely cannot say enough good about outdoor reset and near-constant circulation. It has completely changed not only our fuel use but also the thermal characteristics of the house. This house is full of fin-tube baseboard. The house just IS the set temp. Set back a couple degrees for sleeping; takes a few hours to recover, but otherwise no fluctuations. Just nice, mellow, constant heat. Great stuff.
#17
05-04-07, 06:57 PM
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Another you might want to look at is Crown's CT series. I don't know how they compare on price with the Biasi since nobody around here carries the Biasi, but the quality & performance is certainly there. I have a CT-3 in my own home & love it. BTW, Burnham owns Crown (rebate???).
http://www.crownboiler.com/products/res_oil/free_c.asp
http://www.crownboiler.com/products/res_oil/free_c.asp
#18
05-05-07, 04:43 AM
Looked at the Crown too. It sports higher AFUE, but it's almost 150 lbs heavier - I assume this is mostly the heat exchanger, which I assume makes _some_ difference in efficiency during start-stop operation.
What's the price of a CT-3 with a Riello? Houseneeds sells the Biasi online - seems to be around $1,700 for boiler and burner.
What's the price of a CT-3 with a Riello? Houseneeds sells the Biasi online - seems to be around $1,700 for boiler and burner.
#20
05-07-07, 05:21 AM
@xiphias
What boiler do you use? My list is still down to the Biasi B10 (I don't seem to be able to locate an SG series price - that line has a model that seems sized just right), the Burnham LE (unless I hear really bad things about it, and provided they'll give me a rebate on it) or the Crown CT. Especially when using the DOE numbers all systems are oversized anyway - I just need to add sq ft. to the house
How is the thermal bypass hooked up in a multi-zone system?
The Tekmars are pretty pricey - the 260, which has the DHW controls, is close to $400. Not sure how much extra savings come from the DHW post purge and other 'drain the BTUs' kind of things it has over the 256 model - although I'm not even sure whether the 256 can be used in a DHW system. Do you know?
Getting closer to the answer
What boiler do you use? My list is still down to the Biasi B10 (I don't seem to be able to locate an SG series price - that line has a model that seems sized just right), the Burnham LE (unless I hear really bad things about it, and provided they'll give me a rebate on it) or the Crown CT. Especially when using the DOE numbers all systems are oversized anyway - I just need to add sq ft. to the house
How is the thermal bypass hooked up in a multi-zone system?
The Tekmars are pretty pricey - the 260, which has the DHW controls, is close to $400. Not sure how much extra savings come from the DHW post purge and other 'drain the BTUs' kind of things it has over the 256 model - although I'm not even sure whether the 256 can be used in a DHW system. Do you know?
Getting closer to the answer
#21
05-07-07, 05:28 AM
And just to ease my mind: cold start cast iron, provided it has _some_ regular running time, does not have a significantly shorter life than steel?
Is there any good (proven) reason to prefer a steel heat exchanger over cast iron, or is the overall design what creates the efficiency/longevity?
Is there any good (proven) reason to prefer a steel heat exchanger over cast iron, or is the overall design what creates the efficiency/longevity?
#22
05-07-07, 09:26 AM
I have a Burnham Revolution (RV4; 84k DOE), which has its own built-in primary/secondary pumping arrangement, so doesn't need a thermic bypass. tekmar 260 controller. 40 gal indirect. The 260 (compared to the 256) has the DHW capability. The 260 is a nice control. Not too fancy, not too simple. The next step up is about double the price, at which point payback becomes rather long. In crunching my numbers, I think the payback for the 260 will be realized in its second season. My heating bill is down anywhere from 10-23% per month.
Look around here for threads on the installation of a Danfoss thermic bypass.
Others can speak to the steel vs. cast-iron. I think both boilers, if well-made and well-installed, probably have similar lifespans.
Look around here for threads on the installation of a Danfoss thermic bypass.
Others can speak to the steel vs. cast-iron. I think both boilers, if well-made and well-installed, probably have similar lifespans.
#23
05-07-07, 09:47 AM
So I looked at the 260 wiring diagrams - am I to understand I DON'T need a separate multi-zone controller if I go with this? I also see the multi-pump setup includes a bunch of Tekmar 003 relays - where is all this stuff mounted?
#24
05-07-07, 11:47 AM
You do need a controller. A Taco ZVC would serve quite nicely, tied into the tekmar 260. The tekmar 260 can't do indirect priority with a zone valve, only a pump. However, you could use the ZVC to achieve priority using its priority zone, then set the 260 to "pump" and it would be none the wiser (I discussed this with Taco during my deliberations of pumps vs. valves).
Another way to do this without a tekmar would be to use a Taco ZVC-EXP, then add the PC700 reset, the PC600 post-purge timer, and the PC605 priority protection card. You'd end up at nearly the price of the tekmar 260 with basically the same functionality. (Both the PC600 and 605 would be rather optional.) FWIW, the PC700 has the same guts as the tekmar 256 (tekmar makes a lot of controls that are rebranded by others such as Taco, Viega, Burnham, etc.).
My personal order of preference for zoning and control for a simple 2-zone system plus indirect would be:
1) pump on each zone; Taco SR for relay; tekmar 260 for overall control;
2) space heating on zone valves; pump on indirect. Taco ZVC for zone control; tekmar 260 for overall control;
3) all zone valves; Taco ZVC-EXP with expansion modules as described above.
The SR and the 260 have an effective footprint of about a shoebox each. Mount them on a wall somewhere out of the way of water and for easy access, and you're all set. This stuff can be wired and mounted very cleanly.
What I like about the Taco ZVC and SR is that it's pretty much everything in one box. Very simple to set up and wire.
Another way to do this without a tekmar would be to use a Taco ZVC-EXP, then add the PC700 reset, the PC600 post-purge timer, and the PC605 priority protection card. You'd end up at nearly the price of the tekmar 260 with basically the same functionality. (Both the PC600 and 605 would be rather optional.) FWIW, the PC700 has the same guts as the tekmar 256 (tekmar makes a lot of controls that are rebranded by others such as Taco, Viega, Burnham, etc.).
My personal order of preference for zoning and control for a simple 2-zone system plus indirect would be:
1) pump on each zone; Taco SR for relay; tekmar 260 for overall control;
2) space heating on zone valves; pump on indirect. Taco ZVC for zone control; tekmar 260 for overall control;
3) all zone valves; Taco ZVC-EXP with expansion modules as described above.
The SR and the 260 have an effective footprint of about a shoebox each. Mount them on a wall somewhere out of the way of water and for easy access, and you're all set. This stuff can be wired and mounted very cleanly.
What I like about the Taco ZVC and SR is that it's pretty much everything in one box. Very simple to set up and wire.
#25
05-08-07, 08:56 AM
I think the SR - 260 combo sounds good. Now, for wiring, and for the 260 to do effective DHW management, I assume the wiring would look something like:
- Heating zone pumps on the SR and the priority zone pump out unused
- DHW zone pump on the 260 DHW pump control and 260 heating pump out unused
- DHW aquastat on the 260 DHW demand input
- SR X-X end-to-end switch output on the 260 boiler demand input
Now how does that leave necessary connections for DHW priority? If the SR controls the zone pumps, how would the 260 signal the SR to turn them off for the DHW cycles? Would one duplicate the DHW aquastat signal via relays and also feed it into the priority zone on the SR, just so it turns off the other pumps, or would the 260 somehow feed back into the SR (?)
- Heating zone pumps on the SR and the priority zone pump out unused
- DHW zone pump on the 260 DHW pump control and 260 heating pump out unused
- DHW aquastat on the 260 DHW demand input
- SR X-X end-to-end switch output on the 260 boiler demand input
Now how does that leave necessary connections for DHW priority? If the SR controls the zone pumps, how would the 260 signal the SR to turn them off for the DHW cycles? Would one duplicate the DHW aquastat signal via relays and also feed it into the priority zone on the SR, just so it turns off the other pumps, or would the 260 somehow feed back into the SR (?)
#26
05-08-07, 10:20 AM
Our regional tekmar rep said this is the most common question they get (several times/week), as it briefly stumped my electrician as well. The answer is in a wiring diagram I got from them. I can post to photobucket, maybe later today. Basically it's as described in your first and third items. The DHW on the 260 needs 24V to make; you can pull it off the SR or use a separate transformer. But the DHW pump is not wired through the SR directly -- you're right.
#28
05-08-07, 11:23 AM
Thanks - that's a helpful diagram.
Still leaves a question - assume I want to use DHW priority (and maybe it's just not possible), how does the 260 signal the SR that it needs to turn off all zone pumps when running a priority cycle? It seems the 260 does not feed back into the SR or pumps?
Still leaves a question - assume I want to use DHW priority (and maybe it's just not possible), how does the 260 signal the SR that it needs to turn off all zone pumps when running a priority cycle? It seems the 260 does not feed back into the SR or pumps?
#29
05-08-07, 05:04 PM
It does, by turning off P1, which is wired to the SR. Check out A 260-4 in the tekmar 260 application guide.
http://www.tekmarcontrols.com/literature/acrobat/a260.pdf
And the priority and post-purge stuff does work quite nicely.
http://www.tekmarcontrols.com/literature/acrobat/a260.pdf
And the priority and post-purge stuff does work quite nicely.
#30
05-08-07, 05:23 PM
I think I _almost_ got it. P1 is line voltage - normally powering the zone pump on the 260. So would it be used as power input to the SR, basically shutting it down by powering off in case of DHW priority?
