Condensing Boiler and FinTube Baseboard

CMadatMe

Curious as to what feedback you guys have had from your customers on those retro-fit jobs where you changed out an old guzzler and installed a condensing boiler with existing fin tube.

On average where have you found that you could comfortably start your heating curve? So far I have been able to start at 160 for my design day without any comfort issues, Are you guys finding the same? Do you feel that your customers are experiencing pay back for the added investment?



I know everything is predicated from heat loss and existing emmitters so every job is different but I am finding most homes are about 25-30% over radiated so we have been able to take advantage of it.



Thanks and Happy New Year to All.

icesailor

Condensing Boiler & fin tube:

I can't answer your question the way you asked but I would say that any time you do a boiler change, you should do an accurate heat loss on the structure and then measure the radiation. It depends on what factors the designer used for heat loss. And then, the temperature selected for the emitters. For example, if you use 180 degrees for your max design temperature on emitters, they are oversized until you reach design day and temperature. But if you ran the system at 160, they would be undersized for the same situation. The heat loss factors could have been improved since the origonal installation. Additional spaces may have been added. I don't think that there is a one size fits all.

That "25% to 30% number seems high but designers who are often salespersons, do not want to get a call that a structure is cold. If you don't have enough radiation, you are pretty much screwed. But, if you design a system on 180 degrees, you know that you have a big cushion to fall back on by going to 200 degrees. If you design for 160 or 150, you need a lot more radiation to heat the structure at those temperature. Don't mistake a lower design temperature for over radiation.

Robert O'Brien

Chris

You're right,I was surprised by what low water temps are necessary,unpleasantly on a couple of non condensing units!

Jean-David Beyer

I only know about my house.

Since I am not a contractor, I have experience only with my own house. Downstairs is radiant slab at grade; it uses most of the required heating. Upstairs had things that looked like little radiators in a box, but if you looked inside, it had 3 feet of finned copper tube. It was always cold up there because the house had only one zone, and the hot water was set lower to keep the downstairs floors from getting too hot. Even so, the asphalt tiles would not stay down very well.



My former contractor, who replaced the boiler did some additional work for me at the same time. I calculated the heat loss, since he seemed disinclined to do that, and had hm split the system into two zones: upstairs (finned tube) and downstairs (radiant in slab). I had him replace the two toy radiators with 14 feet of Slant/Fin in each of the two rooms (the width, under the windows, of the two rooms). I should be able to run the upstairs with a maximum of 134F water when it gets to about 0F outside, and design day around her eis 14F. The coolest water I put in up there is 110 F (outdoor reset), because any lower, and the boiler cycles too frequently when heating only that zone).



It is 52F outside at the moment, so I would be putting 114F water up there if the thermostat were calling for heat, which it is not. 69F up there, which is the set point on the thermostat.



A while ago, when it was above freezing outside, but just barely, I put a two gallon bucket under the condensate drain, and got a full bucket (or more; could not tell) a day most days. When it got even colder, I got more, but cannot tell how much. So I was condensing quite a lot. I assume I condense all the time heating the downstairs, because the supply for that is 120F Max, 110F on design day, and 75F when it is 54F or higher outside. Upstairs it may condense all the time down to design day (supply 132F).



I also have an indirect hot water heater that has 170F supply temperature, so it probably does not condense except during the interval where it starts heating up to that temperature. I assume condensings stops when it gets to 130F.



Here are the settings for my reset curves:

PRIORITY                     1                  2                    3

Description     Units        DHW           Downstairs      Upstairs

System Type                  DHW-direct RAD SLAB       FIN BASE

Max Supply    Degrees F    170          120                  134

Min OD Reset Degrees F                      2                    10

Min Supply      Degrees F                    75                  110

Max OD Reset Degrees F                   54                    60

CMadatMe

Ice

I hear what your saying. I do heat losses and also measure emmitters on every job I get my hands on. The majority of systems I am finding 160 degree water is more than adequate for design conditions based off the heat losses. It's funny how back in the day the installers were helping us out today by wrapping those walls with baseboard. Without the past mistakes of over radiating we would be unable to take advantage and squeeze out the efficiencies in the mod/cons.



I also have a few jobs where a zone came up short and we just swapped the residential for the higher capacity board in the zone. That way we could use the same footprint without having to change any piping. Its just a matter of educating the customer and letting them make the decision based off a little education.



Your right. Every job has its own need and is the primary reason why a heat loss is a necessity. Now more important than it was in the past. It's still funny how you go to a consumers house and start breaking out the tape and they say, what are you doing? The last three guys didn't do that. It always begins the educational piece which in turn gives them the sense that you really are looking out for them and allowing them to make the right deicision on how they are going to invest their money.

CMadatMe

Bob

I know. I was on a few jobs in Dec with Vitodens 100's. All baseboard. Outdoor temp was in the low thirties boilers were delivering 130 degree water and the homes were a comfortable 70.



Every homeowner I talk to after the installs say they can't believe how comfortable the home is. It just stays constant and comfortable. These job also all have Grundfoss Alphas as system pumps zone with valves. I wonder in my head how much of a role the Alpha pump plays in it.



By the way, your homeowner sent me a e-mail via the wall asking me about how to maximize his new install. Told him call you don't ask me as your more familiar with the job than I. I also told him he was in good hands so ask. I think he wants Vitotrol 300. I did provide him some basic info on it.

icesailor

Mixing Baseboard:

JDB,

Your situation comes about when installers don't have that old experience of fixing the problems of others.

IMO, you must be very careful with mixing heating types in the same zone. That's what they make zone valves for. The problem you describe is contrary to the laws of physics. It the two floors have heat, the second floor gets hotter because hot air rises. But, when you have a radiant floor, there is very little heat convection from the first floor to the second floor. The second floor was cold because it wasn't being "gifted" by the heat of the first floor. And those funny little boxes with the fin tube inside, were very much more likely to have been able to have heated the whole second floor. And you added 14' (8400s @ 600' water) to each room. I have a book that lists the EDR output of them. It's A choice when you have someone that doesn't want baseboard. That second floor zone didn't work because of bad thermostat placement and the zone being out of balance. You also should never install cast iron radiators or baseboard on the same zone as fin tube baseboard. They emit differently.

It's really tough for some of us to see a job that at one time, worked well. And then, some hot shot got hold of it and turned it in to a horror show. And someone wants us to fix it.

You should see what happens when you have AC on two open floors. The second floor is barely cold and the AC unit runs constantly. The first floor is like a icebox and the compressor never runs. All the cold air just flows down the stairs and the heat from the ceilings on the first floor, just flow upstairs.

Jean-David Beyer

mixing heating types in the same zone.

I was lucky about that. My downstairs zone is all in-slab radiant. My upstairs is finned-tube baseboard. Upstairs and downstairs were all a single zone, and the thermostat was downstairs. Funny thermostat: it had 120 volt contacts that ran the circulator. The boiler was "always hot" or whatever the opposite of cold-start is called.



So, they certainly used different heating types on the same zone. I had that changed to be two zones, baseboard upstairs and radiant downstairs, each with its own thermostat, of course. The baseboard upstairs was ineffective because I estimate it was getting 130 to 140F water supplied to it, and since it was only three feet long in each room, not much heat came out, and then only if the thermostat downstairs was unsatisfied. I know the "radiators" probably gave out a little more heat than just plain baseboard, because they were metal boxes open at the bottom and slots near the top about 18 inches high, and the chimney effect may have gotten more airflow through the fins But ignoring that, 3 feet of baseboard would have to give out 3250 BTU/hr on very cold days, and I do not think those toy radiators could have done that even with 180F water; more like 1800 BTU/hr.



I always wondered about the heat from downstairs not going up very effectively. My contractor did not want to guarantee I could maintain the desired temperature upstairs for fear the heat from downstairs would overheat the upstairs even if that zone were always off. I knew that would not be a problem, and it has not been. I have the upstairs and downstairs thermostats both set to 69F (I setback to 67F upstairs at night) and they both run, though seldom at the same times except on very cold days. My zones are done with circulators. The contractor explained why, but in my case I do not think it really matters much, except for the electricity to run two of them instead of just one.



I did not add 14 feet of baseboard to each room. I replaced the toy radiators with 14 feet of baseboard in each room. As far as I know, the heat upstairs never worked well. From the appearance of the house when I bought it, the couple who owned it before me never used the upstairs. They had no children and were the original owners. That amount of baseboard I selected because I wanted to run as low a temperature as possible in the baseboard so I got maximum condensing from the boiler. Anything longer than 14 feet would have required some structural problems solved, so I picked that, and it calculates out to about 130 degrees at a little colder than design day. I have no cast iron in the system.

icesailor

Fin Tube Baseboard/ Convectors

JDB,

Checkout the site below. Those dinky little heaters probably gave out more heat than the baseboard that you replaced it with. As you vaguely describe them, they may have given out more than 6000 BTU's each. They give out a lot more heat than you realize. And your contractor was not aware of. It comes from experience and asking questions of the supply house that you buy from. The supplier I purchase 99% of my materials has on hand some excellent, experienced people that know what they are doing. When I pay a little more for what I buy, I pay with the knowledge that I can ask questions and get the right answers. Before your contractor suggested changing anything, he should have suggested splitting up the zones. Heating 101. Even the old dead dogs always put two floors on two thermostats/zones. So, I wonder, going back even farther, what the heck was that only thermostat doing as a line voltage thermostat and running things? It sounds like the person who installed the system in the first place was an engineer who knew it all. You're dealing with the fallout.

http://www.beacon-morris.com/html/beacon_morris_convector.asp

Then select "Convector Catalog BMCV-8R. Pick the one that you had. Go down to the water sizes. The first ones are steam.

It saddens mwe that there are so many out there who can not or will not use the resources available to them. How is someone to learn if they don't ask questions?

meplumber

Similar findings.

Chris, I have had similar findings on the curves. 



I almost never put a Vitodens 200 on baseboard due to the 167 deg built in high limit.  But did a lot of Buderus 142's and now Vitodens 100's on baseboard with good results.  Other 142 problems aside.  I also use the Alpha. 



Of course it varies house for house but I am finding that something in the 160-170 range for design day is working.  But not always.  If a house is close, I don't risk it.  I go with a 124 blue or go to oil.



Good Luck.

CMadatMe

Meplumber

Just an fyi. The Vitodens 200 has been changed to max water temp of 176 same as the 100. Its nice to here similar results.

icesailor

Condensing Boiler/Fin Tube, Fan convector units:

How high can you set the Vitoden 100's?

Mine are never easy. I am doing this small converted barn where there is no room for anything. The owner despises the look of most any heat emitting unit. I have a space at the bottom of 1st floor stairs that is a hallway with two outside openings, the stairs to the upstairs Liv. Rm., and the door into the garage, a door into a bathroom and a door into a bedroom. I used a B/M W-42 here and a K-42 under the vanity. No room for anything else. After a year (that's another story), the owner, after rejecting every type of heater I could find, we finally found these "Smith's Environmental" floor units that are really nice. They even have floor grills that were acceptable so I didn't need to make matching wood grates. 3 upstairs in the Kitchen/Liv. Room and one in the bedroom. And a fan cabinet unit in the garage/studio. So, it is all fan coils. The only way you can heat this place is with the fans. The second floor is a zone with three floor units. Two would be barely enough at design day. Three is much better because it now gives you better air circulation in the space which is a cathedral ceiling with windows, 360' and a outside door facing North to a deck. One unit is by the deck door and the stairs leading back downstairs. You will get huge cold fall from the cold air on the floor going down the stairs and heat rising from the heat in the hallway, downstairs. A V-200 at 167 Max would be death. It needs to be able to go higher. I can't find the info on the V-100 on how high it can go.

So, here's the problem. In that last NE storm, where they are still digging out in New York and New Jersey, it blew OVER 80 MPH during the storm. For 10 hours, it consistently blew over 50 MPH. I design for zero (0) degrees w/15 MPH. It seldom gets to below 3 degrees but the wind is always there. I can disconnect the L limit thermostats in the fan coils but if the water temp. is low, and it is blowing, it will feel cold. If I can't get this unit to at least go to 180, it's back to the Munchie, my first choice anyway. I just liked the size of the V-100.

From experience, I can never discount wind induced infiltration and heat loss. Although this house is as tight as a tick, the wind will find a way. If the house ends up being cold, I get the blame. If I don't have flexibility, I better make other arrangements.

What you all say?

Jean-David Beyer

BMCV-8R

I do not know if I interpret those tables correctly. While my convectors were not the same brand, they were quite similar. The lowest supply temperature in the tables is170F, and I am certain the supply temperature I actually had was considerably less, probaby less than 140F. It seems I should derate to about 25%. So if I read the tables correctly, the convectors give out about 3800 BTU/hr for a three-foot one with 180F supply. If there was 20F drop (I have no idea, but judging by what I get now, it is less) I would be getting slightly less than 1000 BTU/hour. Back when I had that system, I detected only slight warmth coming out of them. The baseboard I now have throw out much more heat than that, and when it is very cold out, the pipes coming to and from the Slant/Fin get too hot to touch comfortably. I can touch them, but I let go pretty fast. I can tell they are running by holding my hand over the air coming out. With the old ones, I had to touch the fins to tell if they were heating or not.



I believe the old units were designed to be run at 180F, and they got temperatures suitable for radiant in-slab heating, and their efficiency was greatly reduced. Also, if you saw the near-boiler plumbing, you would wonder just how much water circulated. Thisupstairs. The units did have bleaders, and I would blead them once a year. They usually did not need bleeding. I have no idea what the temperature drop was, as the only thermometer was the one on the front of the boiler, and it had a funny bypass arrangement to keep the water circulated to the house to a lower temperature.



The boiler was an old GE boiler from about 1950. I had the installations instructions (just a page or two, not a manual like nowdays), and it was piped as specified by GE. But they did not discuss finned tube convectors or even more than one zone. If you go here:



http://www.heatinghelp.com/files/articles/1025/177.pdf



and look at their Page 11 and 12, you can see the boiler.



I do not think that in 1950, the contractor had a lot of experience with radiant heating. Perhaps GE did not either.



The boiler was kept hot all the time because it had a hot water coil in it to make domestic hot water. This was not actually used in my house, but my neighbors used theirs. And since the boiler was in the garage, you wanted to keep it hot anyway because it would otherwise freeze in the long hours the thermostat was satisfied because the slab had been overheated. No outdoor reset in those days.

Mark Eatherton

For what its worth....

Here is a link to Slantfins baseboard output charts. Contrary to popular belief, they CAN put out heat with entering temperatures of less than 180 degrees F water...



http://slantfin.com/documents/673.pdf



I spoke to a person just last week who said that Slantfins marketing department was very reluctant to release this data, because they didn't have a condensing boiler, and were afraid of losing market share on boiler sales. They now have a condensor in their line up, so I guess the threat has passed.



ME

icesailor

180 degrees:

Why the heck didn't they just make it even and make it 180 degrees? Most US heating equipment is rated at 180 degrees. If they want to sell in the US, why not use US measures. It's probably a metric thing anyway. Celsius. The FAA changed their ATIS air tempreture and humidity from Farenheit to Celsius. It's a PITA because you must remember that 0'C is freezing where 32F is the same. But there are over 2 degrees F to equal Celsuis. If it is going to be foggy, the tempreture and dewpoint must coincide. So, you must listen to the temperature in Celsius and the Dewpoint in the same. If it is 60F and the dewpoint is 60F, you will probably have fog. But if it is 41C temperature and 41C is the dewpoint, you could have a 5 degree swing and not know it. There are some non-metric measures that are better and more accurate.

If you ever get a call from someone that has one of these systems that are so in vogue now, and the people are complaining of not being satisfied, you better ask about it being warm when it is windy. And you better be able to set the curves higher. I don't care how high tech and efficient these systems are, if someone is cold when you aren't there, and it is warm when you get there, you better understand. When people are cold, they don't care how much they are saving. They want to be warm.

I've been there far too many times. If I can just go turn a nob up and solve the problem, I am  hero. If I can't fix the problem because of something that I didn't do but someone else did, YOU are a bum. Sometimes though, the problem is just infiltration. That's not our fault unless we should have allowed more for it. 

CMadatMe

Mestek

Mark, I happen to get my hands on a chart that Mestek came up with. Gives you all the correction factors for all board all the way down below 100 degree water. Haven't scanned it in yet. It basically states to take a boards reading at 215 degree water temp and multiply it by the factor given for that water temp.

I'll try to scan it in tomorrow and post it. It's a nice reference piece.

CMadatMe

Vitodens 100

Max water temp is 176 degrees. Did you look at these. Might help you out.

http://www.jaga-usa.com/ProductDetail.aspx?ID=1_7



By the way, did you change those aquastats in the kicks from the standard to the low temps?

icesailor

GE Boilers and temps:

What I was trying to say was that the reason those convectors didn't work was that the system was piped wrong. That (now that I know the age of the system) radiation for the second floor was probably over sized for the rooms. The reason they didn't work was because the units were not getting hot enough water. And if the water to the convectors wasn't getting hot, the system was out of balance. Those old dog designers ALWAYS oversized radiation. They were terrified that they would be blamed for a cold house.

Do you still have that GE boiler? Was it one that had the burner on the top and it fired down? Those things were pigs. They origonally had low pressure burners made by GE. They were awful to work on. They were replaced by a power burner like ABD or Beckett. There was a guy where I work who used them exclusively. There was something unusual about the way you were supposed to pipe them and he did it wrong. He decided that because the burner was on the top, and fired down, you had to pipe them with the supply on the bottom and the return on the top. Every boiler was like this and when piping mono-flows, he had the flow going as such, essentially. backwards. If someone came along and didn't understand this and what he was doing, and changed the boiler to something "normal", it wouldn't flow because he had a check valve on the return, right above the boiler facing the correct way for his piping but in backwards for the new system. And all the mono-flows on the supplies.

1950's radiant slabs were pioneers. But they had a few bugs to work out. Is yours steel piping under the slab? It isn't leaking?

Oh, the crud I have seen.

I wonder if Boiler Bob was the guy who installed this system.

Plumdog_2

Also, regarding outdoor reset:

You can play with your heatloss spreadsheet; and by changing your outdoor design temperature, you can see that the required btu room by room, and the temperature to achieve it, will closely match the default reset curve of most condensing boilers. And because most old-school designs had extreme overkill built-in (boilers about 2-3 times too much input, usually adequate BB length), they will coast along quite nicely at reduced temperatures.

icesailor

Thermostats in fan coil units:

No, the manufacturer just recommends disconnecting them for low water temperature applications. But, glad you asked. They must not offer low temp ones. If I took them out, the fans would run all the time and I would need to run them all through a relay.  That's still doable. The electrician is going to hate me.

I actually like fan coils. Especially in bathrooms. Bathrooms are usually around 1000 BTU's which is less than 1.5 feet of baseboard so you usually put in 3'. With a fan coil, you get 4200 on high speed and 2100 on low speed. It is quiet, the bathroom is toasty warm, and the gals in the house are happy. Life is good. If it is cold, life can be unbearable. And you don't get rusty baseboards that are next to the only place for baseboard. Next to the toilet.

You can BS the guys. Not the gals. It must be genetic. Being able to distinguish BS from the truth in their children. Or the ability to deny the truth. Either way, I find that I am a lousey liar. I just try to tell it like it is. If my wife comes up with something and askes me to do it, and I tell her it can't be done, she just looks at me. Then, I go and do it. She knows.

A customer will ask if this can be done? Not that way but probably this way. It's how much are you willing to spend?

Or,

This thing doesn't work. How long has it been like this? It's always been like that. Here, I'll fix that. There. See you. Bye.

CMadatMe

Beacon Morris

Makes them for the kicks. The allow for 120-105 degree water. The exisiting only are good down to 140. See page 6 of the install manual attached. Page 7 has the part number. They can be ordered through Beacon.

icesailor

Floor heaters:

I just posted a note about my situation but I lost the note. Here;s the units. I now see that they have a line of low temperature products for geothermal. I'll have to go backand check it out.



http://www.smithsenvironmental.com/html/floorkit.html

Jean-David Beyer

I have a chart from Slant/Fin for Base/Line 2000

This is the type I have installed. Mine is type BL-75 (3/4" tubing). It is dated 2007.



If I run 1 GPM through it and 65F air entering, I can expect:



110F 150 BTU/hr/ft

120F 200

130F 250

140F 300

150F 360

160F 430

170F 500

180F 570

190F 630

200F 700

210F 770

220F 810

Jean-David Beyer

Do you still have that GE boiler?

No, they took it away when they installed my Ultra 3. But you have my boiler in mind. It fired from the top, but blew auxiliary air into the bottom. Exhaust went out the bottom of the boiler. By 1980, the burner quit, leaking oil all over the floor. There was a little valve in them that had to be replaced, but GE was out of that business for quite a while, so no valve was available. The company took out that burner, plugged the top and bottom, and took off an inspection door on the side and fired a new Beckett Flame Retention burner in there. That worked fine, other than burning out HV transformers. After they replaced one with a solid state electrozapper, it worked fine ever since. But I wanted to get the 1000 gallon oil tank out of there before it leaked. I was, unfortunately, a little too late for that.



All copper piping. Slab has 1/2 inch (mostly) copper tubing in it. As far as I can tell, it is not leaking. I can turn off the makeup water for a month and the pressure does not go down. The gauge is now 18 months old and seems to be working. For example, if the circulator to the indirect switches on, the pressure drops by several pounds because the gauge is at the output of the boiler's heat exchanger, and when the circulator is off, pressure goes back up to what it is supposed to be.



I do not think the guy piped it wrong. According to GE, you were supposed to pipe the return into the top and take the supply from the bottom. The piping was very strange, though. Imagine a loop with the circulator on the right pumping up. then the water went to the left and off to the house, the water returned and came back to the circulator on the bottom. So far so good, but no water going to or from the boiler.

The boiler was connected between the top and bottom pipe between the circulator and the house. The main pipe there was one inch, but the connection pipe to and from the boiler wa 3/4 inch, and there was a valve you could use to throttle the water through the boiler so that the water delivered to the house was lower than the boiler. That is all described in the GE installation instructions. So a 1 inch pipe disappeared into the slab and five 1/2 inch pipes came back out. There was a globe valve in the 1 inch supply pipe with 1/2 inch pipe going upstairs. To get more heat upstairs, you closed that globe valve more. But at some point, you interfered with the heat to downstairs too much, but still did not get enough upstairs.



Anyhow, now with a new boiler I get all the flow I want upstairs and all the flow I want downstairs, because they are now separate zones, and separate circulators, and I can run different temperatures in each. I still think those "radiators" would not have put out the heat I need up there unless I put something like 180F in them, if I read those charts you pointed to correctly. At the temperature I could deliver, they would put out only about 1000 BTU/hour, and I sometimes might need about 3000.

Jean-David Beyer

they are still digging out in New York and New Jersey, it blew OVER 80 MPH during the storm. For 10 hours, it consistently blew over 50 MPH. I design for zero (0) degrees w/15 MPH.

I am in New Jersey and it was not that bad, except for incompetent plowing of streets. It did not go below 13.3F here since September 1, probably last weekend. The winds were fairly high, but I do not know exactly. I have a Cape Cod house, and an attached garage. Drifting was so bad I could not see out the second story windows at first, because the drifting blew up enough snow to completely cover them. Around the house downstairs, the snow was about 5 feet deep. I could not open the doors. I had to open the kitchen door to outside and remove the glass from the storm door to get out. I imagine around my house it was 3 to 4 feet deep there on the average. It took a neighbor over an hour with a snow blower and shovel to clear my sidewalk (about 180 feet) one snow blower wide. It usually takes a little less than 1/2 hour. Design day around here is 14F. Last winter it got down to 9.6F or so for a little bit one night but I do not know how long. It was warmer than that when I woke up. My heating system could deal with that.



I used to live in Buffalo, N.Y., and we would get about 1/2 dozen storms like this each winter. I do not miss that at all.

icesailor

Storms:

Wussies.

The planes don't fly when it gets over 35. It makes for hard landings. I've been through some interesting landings.

Don't be too hard on the plow operators. Since everything is privatized, all the DPW plow operators get canned and it goes to private contractors who have drivers that can barely back up. Let alone, drive forward without hitting the cars on the right. And it doesn't snow enough in NJ to give then the practice they need.  I do my "walk" (driveway) 500+ feet long with my 50HP John Deere tractor with a 6' bucket. It takes me about a half hour.

icesailor

Fin tube base:

That must be #15 Baseboard. It has a lower rating. I always use #30. It rates at 600 BTU's at 180 degrees. It's an easier # for me to use in my head. I can't count too high.