Questions About Lengthening A Hot Water Baseboard Heating Unit In One Room?

Reply

  #1  
Old 01-03-13, 11:23 AM
Member
Thread Starter
Join Date: Aug 2009
Location: New York
Posts: 247
Received 0 Votes on 0 Posts
Questions About Lengthening A Hot Water Baseboard Heating Unit In One Room?

I have a hot water baseboard heating system that currently works well. The master bedroom is the furthest away from the boiler and is the coolest room in the house which is OK since we like it cooler for sleeping comfort.

Presently, the master bedroom has carpet over a solid oak strip floor that has been in place since we moved into the house 30+ years ago.

We are thinking about removing the carpet and not replacing it since we prefer the look of the oak floor but are concerned the room will be noticeably cooler than it presently is and we may need to supplement the heating system to compensate.

The room is 15' x 20' with a finned baseboard unit along a 15' outside wall that has a double window.

I've tried checking the archives to find the answer and realize there are recommended limits to the length of the heating runs. (or loops as they are sometimes called) The current system is piped with 3/4" copper. The house is a ranch with what has been called a perimeter heating system where there are two loops feeding off the boiler with one feeding the front side of the house and the one feeding the back side and they then come together at the end of the house opposite the boiler with a center return back to the boiler. Each loop has a separate circulating pump.

I have two questions:

1. Can I keep things simple by just extending the existing baseboard unit along part of the 20' outside wall to add some additional heat without incurring negative consequences?

(would not be lengthening the run just making a 90 degree turn at the corner of the room and replacing some of the copper pipe that connects to the next room with a finned baseboard unit)

2. Is the 67' maximum recommended run length for 3/4" copper referring to just the finned portion of the baseboard heating unit, or the total length of copper piping plus the finned baseboard heating units?


Any input or guidance would be appreciated.

Thank you
 
Sponsored Links
  #2  
Old 01-03-13, 11:34 AM
Member
Join Date: Jan 2012
Location: Canada
Posts: 2,739
Received 15 Votes on 15 Posts
Do you know what make/model the finned baseboard you have now is?
About how old is it?

I'm thinking the easiest might be to simply upgrade to a higher output finned baseboard.
I know with my own (40+ yrs old) finned baseboards, I can upgrade baseboards that have more then double the output. Would be a fairly simple remove the old, install the new with no extra work.
 
  #3  
Old 01-03-13, 01:09 PM
Member
Thread Starter
Join Date: Aug 2009
Location: New York
Posts: 247
Received 0 Votes on 0 Posts
Would be a fairly simple remove the old, install the new with no extra work
I'm assuming I would need to break all the old solder connections, remove the old baseboards and solder in the new baseboards?

My existing baseboards are Slant Fin and are about 35 years old.
 
  #4  
Old 01-03-13, 01:20 PM
Member
Join Date: Jan 2012
Location: Canada
Posts: 2,739
Received 15 Votes on 15 Posts
I'm assuming I would need to break all the old solder connections, remove the old baseboards and solder in the new baseboards?
Assuming yours are the same or very similar to mine, your assumption would be correct from what I have seen.
The baseboards I'm looking at picking up to replace mine would see me cutting the pipes just after the 90's coming up from the floor and soldering in the new baseboard. More then likely, you'll probably have to cut one side, desolder the other, then return to the cut end and desolder the remaining piece. Clean both ends, and then install/solder the new one in place.

I'm no pro with a propane torch (getting pretty damn good now though), and I don't see it as a tough task. Shouldn't be too hard provided you are reasonably good with a torch.
 
  #5  
Old 01-03-13, 02:31 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 2 Votes on 2 Posts
I have not used them yet, but these have very impressive output numbers when both the upper and lower tubes are paralleled.

Smith Environmental Hydronic Baseboards. Heating Edge Hydronic Baseboard. Hydronic Heating Systems - Radiant Heating System, Solar Heating, Geothermal Heating

Perhaps these are the ones Mike is talking about?

67' is just the finned RADIATING portion, not the connecting pipework. I wouldn't worry about 'hitting the wall' at 67' though... if you have to go a little over it's not the end of the world.

Do remember though, that the 67' number is based on the BTU/FT rating of the baseboard used.

3/4" pipe at reasonable 4 GPM design flow means that 3/4" can carry a heat load of appx 40K BTU.

If you use baseboard rated at say 600 BTU per foot, you divide 600 into 40,000 and that's where the 67' comes from.

This would give the 'standard' design value of 20 between supply and return.

So, say you replaced that baseboard with a product of TWICE the heat output, but used the same length... you would have to count that as TWICE as many feet...

So, 40000 BTU divided by 1200 BTU / FT and you would only be 'allowed' 33' of the new baseboard on this run.

OK, time to clock out...
more later...
 
  #6  
Old 01-03-13, 02:44 PM
Member
Join Date: Mar 2009
Location: USA
Posts: 675
Received 1 Vote on 1 Post
The baseboard

You didn't say what the room is over. Is it over another room. a garage, a cellar, or the ground? Based on the answer, you may have the info you need whether you need anything at all.
Sid
 
  #7  
Old 01-03-13, 03:39 PM
Member
Thread Starter
Join Date: Aug 2009
Location: New York
Posts: 247
Received 0 Votes on 0 Posts
The room is 15' wide and 20' long. One 15' wall is an outside wall where the existing baseboard heating unit is located. One 20' wall is an outside wall where there currently is no baseboard heat and the wall I was thinking about adding additional baseboard units to.

The room is over both a below grade basement as well as a crawl space. The crawl space is under the first 8' starting at the outside wall where the existing baseboard unit is located and the balance of 12' of the room's length is over the basement. The crawl space has an opening to the cellar about 2.5' x 2.5' and seldom drops below 40 degrees on the coldest days of winter and is normally 50+ degrees.

The baseboard units Northern Mike and NJ Trooper pointed to are pretty impressive. I measured the finned Radiating portion of my units on the front loop where this room is located and the existing total is 48'. I believe that means I could either replace the existing 15' unit with the new twin tube units from Smith Environmental or extend my existing unit along the outside 20' wall and still be within the 67' guideline.

I have about 20' of extra baseboard matching my existing make/model that would blend in perfectly so the cost is zero. 15 feet of the Smith Environmental product would cost about $450 plus s&h plus any sales tax. My labor would probably be similar.

So one question becomes which way makes the most sense?
 
  #8  
Old 01-03-13, 05:50 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 2 Votes on 2 Posts
So one question becomes which way makes the most sense?
I'm all about the bucks, and if I had a piece of unused board, in it would go.

Chances are pretty good that 15' of the Smith would be too much and would steam you out... if going with that I would probably only use about 10' or so.

Before I did anything though, I might consider insulating the underside of the floor, especially since the concern about removing the carpeting.

15' of baseboard in that room should be more than enough under normal circumstances though, at 600 BTU / FT you are looking at 9000 BTU (with 180 water). Since it's out on the end, the water may be a bit cooler though, reducing it's output somewhat.

At a ballpark figure of 25 BTU / SQ FT of heat loss (typical) you should only need 7500 BTU to heat that room.

How long since the cover on the BB was removed and the dust vacuumed out from the fins? You would be surprised at the difference that can make.

Also, you say the carpeting is wall to wall? Is it obstructing the bottom air opening into the BB? If so, removing the carpeting might improve it enough so that you won't need to add more...
 
  #9  
Old 01-04-13, 07:06 AM
Member
Join Date: Jan 2012
Location: Canada
Posts: 2,739
Received 15 Votes on 15 Posts
NJ Trooper is correct about the baseboard I had in mind. Given the length, it would be overkill for sure. In my case, my radiant output on my one floor is way too low, so I'll be ordering a few of these or similar.
Would you happen to have the calculation handy that you used to calculate the max btu of 3/4" pipe?
I'd be interested to see what my 1 1/4" feed loop is capable of. I know that with my existing rad setup, the return water is not a whole lot cooler then the hotside.

targa, being that you have baseboards on hand, ya, I would look at that direction as well as maybe better insulation. If you didn't have that on hand, I'd probably suggest going with a high output, but shorter rad. It'll give you more useable wall space.
 
  #10  
Old 01-04-13, 07:46 AM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 2 Votes on 2 Posts
Mike, 1-1/4" pipe will support about 150-160K BTU. So if you aren't pulling that much heat out the return will be almost the same temp.
 
  #11  
Old 01-04-13, 09:21 AM
Member
Thread Starter
Join Date: Aug 2009
Location: New York
Posts: 247
Received 0 Votes on 0 Posts
Well, it has probably been a while since the covers were removed and the fins vacuumed and the carpet is leaving a relatively small gap on the bottom of the cover so removing the carpet and cleaning would probably help some. The other issue is that there is some furniture along the wall that has to remain which I assume will also affect the heat output?

Btw, the floor under the entire room including the crawl space is insulated with 6 1/4" (R-19 ) roll insulation.

One question I have when everything is considered ( end of heating loop, furniture in front of 6' - 7' of the baseboard units and removing the carpet) is how much additional baseboard ( same as the existing ) would you add on to compensate? I have two complete 8' pieces with covers.

Thank you
 
  #12  
Old 01-04-13, 09:57 AM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 2 Votes on 2 Posts
How much... kind of a tough call.

Don't really want to tell you to install it all and then you end up putting aluminum foil over most of it to cut down the heat...

Don't want to tell you to install 'not enough' and still have a cool room.

But I would guess that based on what we know, on 8' section would probably do the trick..

it is a guess though... I can't imagine that the room would need more than 50% additional!
 
  #13  
Old 01-04-13, 10:13 AM
Member
Thread Starter
Join Date: Aug 2009
Location: New York
Posts: 247
Received 0 Votes on 0 Posts
My particular Slant Fin baseboards have the adjustable louver near the top that allows you to turn it in such a way that it attempts to close off much of the air flowing up through the fins.

My thought is that for aesthetics installing both 8' pieces of baseboard would occupy virtually the entire wall and look more uniform and if it was too warm I could close down some of the louvers.

Don't know if these work because I've never closed them off. Do you know whether these allow enough control over reducing the heat output?

Thanks
 
  #14  
Old 01-04-13, 10:33 AM
Member
Join Date: Jan 2012
Location: Canada
Posts: 2,739
Received 15 Votes on 15 Posts
My particular Slant Fin baseboards have the adjustable louver near the top that allows you to turn it in such a way that it attempts to close off much of the air flowing up through the fins.

My thought is that for aesthetics installing both 8' pieces of baseboard would occupy virtually the entire wall and look more uniform and if it was too warm I could close down some of the louvers.

Don't know if these work because I've never closed them off. Do you know whether these allow enough control over reducing the heat output?

Thanks
I don't think that top louver will do enough for you. I've got an issue with my boys bedrooms where they are over radiated compared to the rest of the second floor. Closing that top piece didn't reduce the heat much.
 
  #15  
Old 01-04-13, 01:09 PM
Member
Thread Starter
Join Date: Aug 2009
Location: New York
Posts: 247
Received 0 Votes on 0 Posts
Thanks Northern Mike and NJ Trooper for the information and advice.

I think adding one 8' section of baseboard is the prudent thing to do.
 
  #16  
Old 01-04-13, 05:42 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 2 Votes on 2 Posts
The top louvers do work to a degree. I close all mine in the summer to keep the dust out.

You will still get a fair amount of heat out anyway...

The heavy duty foil over the finned portion works great though.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes
 
Ask a Question
Question Title:
Description:
Your question will be posted in: