Baseboard heat supply line

[Steves0927]

i just got done tiling the walls in my bathroom. now the riser pipe for the baseboard heat is a 1/8 of an inch away-from the wall on one end and 1 1/4 on the other I removed the old rusty element before construction and have a 3/4 pipe in place for the time being
I do not have access to the riser pipe from below
Any ideas how to angle the one end

 

[Plumber69]

huh?

 

[Sponsor]

 

[Steves0927]

Here is a pic if the riser out of the floor next to the tile
I was thinking of just leaving the 3/4 pipe in place and covering it with the heater cover
Will that still generate enough heat in a 5x8 bathroom?

 

[Dana]

I need the bigger picture. How much distance is there between the riser pipes?

What size fins and how long was the finned section that was removed?

Are you running a condensing boiler under outdoor reset control, or fixed temperature output on the boiler?

It's nearly impossible that a bare 3/4" pipe is going to be enough to heat the room even if you DON'T box it in with a cover (which would reduce it's output.

To know how much heat it needs, first run a Manual-J heat load calculation on that room, using aggressive assumptions on R-values, window performance and air leakage (eg: pretend it's completely air-tight).

If the heat load is small enough you might do just fine with a heated-towel rack type radiator, which is a nice touch when it works, but could be a hazard if you're running 180F water instead of 110-130F water on the heating system.

With a couple of sweat 45 degree ells and a properly sized nipple you can make the distance from the wall the same on each end, but how far out it NEEDS to be depends on the radiation choice.

 

[Steves0927]

I cut out a 4 foot slant fin heater
I planned on using a 4 foot slant fin fine line 30 to replace it
Here is a pic of the burner temp
I think I did the load calc right and came up with 386 btu

 

[Dana]

It looks like 160F at the boiler- is that it's peak temp? (It matters.)

If yes, we can assume the average water temp (AWT) through the loop is about 150F or so, which would take about ONE FOOT of fineline 30 to cover the 386 BTU/hr load. A four footer would cook the place if running a high duty cycle with 150F AWT, but a 2-footer would be about right at 120F AWT.

Compare the heat loads and baseboard lengths in other rooms to see if the load/ BTU per foot of baseboard in other rooms on that loop all fall within in a range. They t may be similarly overkill, but if you make the bathroom radiation reasonably proportional in terms of the load / foot of baseboard ratio you won't over or under heat the bathroom.

If the whole place can be heated with 120F water it's good candidate for a condensing boiler, provided there is sufficient radiation to not short-cycle a low-mass boiler into an early grave.

To sanity check the load number, I assume you have something like a 5' x 9' of exterior wall, with perhaps a small (or no) window, with conditioned space both above the ceiling and below the floor?

 

[Steves0927]

It looks like 160F at the boiler- is that it's peak temp? (It matters.)

If yes, we can assume the average water temp (AWT) through the loop is about 150F or so, which would take about ONE FOOT of fineline 30 to cover the 386 BTU/hr load. A four footer would cook the place if running a high duty cycle with 150F AWT, but a 2-footer would be about right at 120F AWT.

Compare the heat loads and baseboard lengths in other rooms to see if the load/ BTU per foot of baseboard in other rooms on that loop all fall within in a range. They t may be similarly overkill, but if you make the bathroom radiation reasonably proportional in terms of the load / foot of baseboard ratio you won't over or under heat the bathroom.

If the whole place can be heated with 120F water it's good candidate for a condensing boiler, provided there is sufficient radiation to not short-cycle a low-mass boiler into an early grave.

To sanity check the load number, I assume you have something like a 5' x 9' of exterior wall, with perhaps a small (or no) window, with conditioned space both above the ceiling and below the floor?

Yes the bathroom is 5 x 8 1 exterior wall with a small window 8 foot ceiling with new insulation it is the second floor of a split level and the second floor is always hot in the winter
The bedroom next to it is so hot I keep the window open 4 inches all winter
My heat is usually set at 67 and the second floor is usually 73

 

[Dana]

Keeping the window open is an expensive solution to the overheating problem. There could be a number of things going on here.

Are both levels operated as a single zone, with the thermostat on the lower level?

Is the lower level above an un-insulated basement?

Houses that run hot on the upper levels, cold on the lower levels in winter usually have an excess of air leakage out of the top of the house, drawing cold outdoor air into the lower level. If you can fix the air leakage at the top floor ceiling, and under the floor in the lower level it almost doesn't matter what air leakage there is in the middle- the stack effect drive is more or less neutralized. Opening the upper level window may cool that room, but it also increases the stack effect infiltration coming into the lower level.

Blower door and infra-red imaging directed air sealing may be able to fix 90% of the issue. If the basement/foundation isn't insulated, fixing that will also warm up the lower level with negligible effect on the upper level.

If this is a split level where the lower level is partly below grade it's probably going to need to be zoned by floor to be truly optimal. The changes in heat load with outdoor temperature is very different between partially below grade and fully above grade spaces.

 

[Steves0927]

It’s a split finished basement 4 feet below grade zone 1
Up 5 steps is main floor over insulated crawl space the up 7 steps to 3 beds and bathroom
Zone 2 is main and second floor thermostats are in basement and main floor
The basement and main floor were insulated in the past year

 

[Dana]

It's almost always better to air-seal prior to insulating, but a blower door & IR camera would still find it all even if there's insulation affecting the flow.

Is the "...insulated crawl space..." insulated at the crawlspace walls (with a few inches of rigid foam), or batts stuffed between the main floor's floor joists, or something else? (Air leakage at the foundation sills and band joists on crawlspaces can really undercut the performance of the batts in joists approach.)

 

[Steves0927]

Just insulated between the joists
Back to the bathroom do you think putting 2 45s on each riser will get the heater far enough from the wall

 

[Dana]

The band joists need to be caulked to the subfloor, foundation sill, and floor joists, and the sill needs to be caulked to the foundation. If the foundation has cracks it too could be leaking air. If it's a VENTED crawlspace there's even bigger leaks to think about.

Air sealing the subfloor between the crawlspace and main floor is usually a fools errand, but that too is important, especially if there are electrical & plumbing penetrations of the subfloor. It's usually more reliable to put down a ground vapor barrier on the floor and insulate/air seal at the crawlspace walls.

 

[Dana]

This is all going pretty far afield of the plumbing & radiation issue with the bathroom. If the rooms on that level all have about the same amount of overheating, sticking with the same heat load per foot of baseboard ratio in the bathroom as other rooms on that level is the right thing to do there.

But fixing the stratification & zone balance issue is still worth pursuing, even if it means breaking up the main & top floor into separately controlled zones.