Home>Discussions>PLUMBING>how much slant fin can i add
2 posts / 0 new
Last post
how much slant fin can i add

Hi I have removed one older stand-alone 3 ft convection unit and replaced it with 2 6t sections (12 ft total) of slant fin base board, i hardly get any heat from them . I've bled the line, no air. Are these supposed to be installed with a pitch so the water flows by gravity into the return line so to speak?

A plumber told me there is too much baseboard and water takes the path of least resistance so it goes into the shorter lengths first, is that true?

Thank you

happy holidays

Robert /nyc

Re: how much slant fin can i add


For the most part you can add as much baseboard as you want, but IT MUST BE PIPED IN SUCH A WAY THAT THE PUMPED WATER AS IT FLOWS THRU THE PIPING CAN'T TAKE ANY DETOURS---I suspect that you've soldered or connected the 2 new sections so that they form a "fork in the road", so the flow of the water inside the piping splits itself up & dissipates the heat.

There ARE other factors involved---for example, some hw piping circuits (the total loop) for a house extend in a single loop for well over 100 feet (beginning at the boiler where the SUPPLY HW is pumped to the baseboards, to the COOLED RETURN LUKEWARM WATER returned to the boiler to be heated again) ---clearly, the temperature of the pumped water starts off at approx 180 degrees when it goes thru the beginning baseboards of the heated space, but by the time it reaches the end of the loop that goes back to the boiler to be re-heated, the pumped water temp has dropped to perhaps under 100 degrees (known as a delta T drop)---if the remodel work you did with your new baseboard sections happens to be at the "cooler" end (near the end of the loop), it will be even harder to get any useable heat out of the new addition---sometimes in these instances the single, long loop has to be divided into 2 zones (zone valves), so that all parts of the house are adequately heated.

Consult the "high performance" site below to examine how water has to flow thru a pipe heating circuit, especially the single pipe arrangement, which is the most common piping circuit used in the heating industry---notice in the "one pipe series loop" that the water has only ONE PATH THAT IT CAN FOLLOW---it begins in the heated boiler (blue box) & is pumped out the left side of the boiler (pump not shown) thru the red line representing the heated water, then goes sequentially thru each of the baseboard/convectors, giving up some of its heat to the convectors, then (orange line) the cooled water is returned to the boiler to be heated & pumped once again thru the convectors.

Please post back to tell us if the 2 sections of baseboard you recently added are near the "end of the line", the "middle of the line", or the "beginning of the line"---if you reconnect them (resolder?) "end to end" as they should be, this may well solve the problem (this can be done in a "serpentine" arrangement to save space [one 3-ft section over the other], as long as the flow of one 3' section of baseboard flows sequentially into the 2nd 3' piece of baseboard)---however, if this repair is being done at a point in the piping arrangement where the heated water has cooled to the point where you may not get enough heat out of the added section ("end of the line"), something else will have to be done to get good heat out of the new baseboard sections----check the water temp gauge situated on the boiler---it should read approx 150 degrees or better (non-condensing boiler) when the system is calling for heat (T-stat turned up), & should go up to 180 degrees to 200 degrees toward the middle & end of the heating cycle----the "high limit control" on the boiler should be set to approx 180 to 200 degrees to make sure you have a good supply of HW being pumped thru the piping to heat the baseboards.

You should be able to FEEL THE PIPING with your fingers near the new repair as the boiler is running & the boiler pump is pumping HW thru the piping---if the HW running thru the piping at that point is hot enough, you won't be able to keep your fingers on the piping more than one or two seconds----if the piping is cooler than that, additional adjustments will have to be done.

Any photos you can post will be helpful----what is the btu output of the boiler (should be on the faceplate of the boiler); what is the approx total length of the HW piping that snakes thru the house rooms as it leaves the boiler (supply piping), goes thru all the rooms & returns to the boiler on the return side?? What is the total square footage of all the spaces being heated in the house??

What did the plumber that was there suggest as a solution to the problem of low heat in the baseboards??

We will continue to work with you if you decide to diy; or you can consult the Yellow Pages under 'Heating Contractors" & check the display ads to get a contractor that specializes in hydronic (hot water) heating systems.


Sponsored Stories

TV Listings

Find TV listings for This Old House and Ask This Old House in your area.