Baseboard Heat for Basement

Astro64

I am just starting to finish my basement. I haven't put up studs yet but laid out the base plates for all the walls. I have a new Burnham High Efficiency system installed about 5 feet off the floor. The installation included stub outs for a zone for the basement as I knew I would be finishing it. I'm thinking I will install the baseboard myself and then use a contractor to perform the final connections to the boiler and the start up of the zone. I have studied as many sites as I can and performed all the analysis of the heat loss in the basement and required heat need to keep the space around 72 degrees when needed. We have had 1 20 degree day so far and the basement was at 50 degrees and that is without walls/insulation. All air gaps have been sealed so it doesn't get too cold in it during the winter months. My questions are: I'm going to have 2 places where I need to bring the heat up to the joists (about 7' 8") Once will be to get passed the exterior door and the other is to tie into the return for the boiler. Should I install purge valves at the top of those 2 rises? My second question is how do I prevent the pipes from banging inside the walls? I'm assuming I'm going to have to run the pipes inside all the exterior walls to get it around the perimeter instead of having 5 places where it rises to the joists. I am thinking of pre-drilling 1 1/4" holes for the 3/4" pipe and using the slant fin riser rings. They are pricey but is there another option so the pipes don't bang in the wall? I will include pics of my system and a layout of the basement space with the amount of heat I'm thinking of installing if someone can help me figure out how to insert them. It's asking for a url but they are jpgs on my computer. Thank you in advance for your help/advice.

Jamie Hall

Yes, you would be well advised to put air release valves -- such as you would use on a radiator -- at the high points. That will make purging much easier.

On the pipes banging. How's that again? Pipes in a hot water heating system should never bang (they shouldn't for steam either, comes to that!). They do need to be properly supported, however, and routed so that they aren't in direct contact with studs or joists or what have you. You also need to provide for expansion and contraction -- which basically means that while the pipe can (and should) be solidly anchored to something at one point, all the other supports need to allow the pipe to move a little along its length (but not laterally) -- or the distance and arrangement needs to be such that the pipes can flex a bit.

mattmia2

You need to know what the supply water design temp is. you need a lot of baseboard to get enough output out of lower temp water, so if the system is designed to run low temp condensing you might have trouble getting enough baseboard. panel radiators could make more sense depending on how the system is designed. if you want to only heat it intermittently when you are using a workshop or something like that, you will want to size it to be able to recover in a reasonable time.

Astro64

Thank you for your responses! I understand the need to allow expansion in length of the pipes and will take that into account. I'm still figuring out how to run all the connecting pipes thru the studs as I can't obviously go below the floor as you would do on a first or second floor. My system currently heats 2 floors of the house and a 900 sq ft space above the garage and does so very efficiently. Matt, my system has a starting water temp of 180 degrees and my understanding is that I could expect a 20 degree drop in water temp over 67 feet of 3/4" baseboard (11% drop in efficiency). I only plan on using 54 feet of baseboard but I have assumed the end of the loop needs to be 11% longer then would be required if the water was at 180 degrees. Does that make sense? Jaimie, I was going to use purge valves at the top of the vertical rises. Are you saying I don't necessarily need to have something I can hook a hose up to and purge but really just need something that will release air?

Astro64

Matt, I have a Burnham Alpine High Efficiency system and I just went into the menu screen and looked at the status and the set point on the boiler is 148 degrees. It is monitoring the supply and return water temps and outside temp. So its not going to put out 180 degrees it will put out 148 degrees. Based on that, I'm assuming the slant fin 30 baseboards aren't going to put out 580 BTU/Linear Foot and I'm going to have to go see if they have a chart that tells me what they will put out at 148 degrees.

mattmia2

You might think about a supply and return loop in the ceiling instead of putting the emitters in the ceiling (ideally arranged so the first emitter to be supplied is the last to connect to the return), just drop down at each emitter instead of trying to make a loop with obstructions. Might put a manual bleeder valve at the high spot of the mains just in case and need to have a drain at the bottom of each emitter section so you can drain it if needed, could be combined with a balancing or isolation valve.

Others can comment better on the drop in water temp, but you tend to not get as much drop in temp as the literature states, the 20 degrees makes the math about heat content of water end up in round numbers. There is something weird in the way manufacturers rate the output of baseboard radiation, the output listed has some percent correction factor to try to mimic the behavior of cast iron radiation.

Are you going to heat this space continuously? If not you probably want more headroom to increase output to recover from a setback in a reasonable amount of time.

There are a bunch of great articles (more like textbook chapters) about hydronic design theory here:
https://www.caleffi.com/usa/en-us/technical-magazine

You would want a purge tee arrangement such that you could shut off a valve in the loop somewhere near the feeder and open a drain somewhere just before the valve and hook up a hose and force water through the loop with the feeder to get most of the air out. Once you have flow, assuming the existing system has good air elimination, it should take care of the rest of the air.

Dan explains it better than I ever could in here:
https://heatinghelp.com/systems-help-center/pumping-away-piping/

mattmia2

The idea is that they will output less but it is supposed to be matching the heat loss, that is the idea of the outdoor reset curve in the boiler. The issue might be that the baseboard might need a curve with a gentler slope than the other emitters in the system.

An outdoor reset curve, in its simplest form, is really just a line with a slope. You configure the boiler with the coldest outdoor temp and the required supply water temp for that outdoor temp and the warmest outdoor temp with the requires supply temp for that outdoor temp and it calculates the supply water temp in between those 2 points based on the current outdoor temp.

Slant Fin has a chart with the output per foot of their baseboard at various supply water temps. You would change the outdoor temp in your heat loss calculations to something near the warmest outdoor temp where you would still be running and you could then find the output needed and the supply water temp needed. You could either add more radiation or change the reset curve if the current curve doesn't give you enough heat.

Astro64

Thanks Matt! A lot of great information. I didn't even think about running it along the ceiling and then drop down to each emitter. I figured I would need air relief at every vertical rise for the returns and that would require a huge effort to bleed the system. It certainly would make installation easier. My intention is to constantly heat the space. Its going to be kept at 65 when not in use and they probably 72 when in use. I'm expecting my daughter and her friends will be hanging out a lot down there and definitely on weekends. I'm going to do more research using the links you provided. I have to say this is probably the one thing I will be doing in the basement that makes me nervous because it can screw up the rest of the house. I have 100% confidence in everything else I do but laying out a heating system is not something I'm experienced at doing. I love a good challenge but if I get too nervous I'll can in the experts. These are pics of my existing system and you can see the stub on the left that was installed for the basement zone to be connected. Hopefully these post in here.

Astro64

Here is the basement layout:

hot_rod

The rest of the home is fin tube baseboard?

Consider a home run system also. Each room or bb gets a supply and return usually with pex or Pex al Pex

Ceiling radiant or panel radiators are also nice options if the system is running low temperature

mattmia2

Panel radiators with thermostatic radiator valves might make a lot of sense in that space. Fin tube could probably be purged with a purge station at the boiler, panel radiators fed from overhead might need to be bled individually to get flow started. Panel radiators usually come with a tapping for a bleed valve.

If that existing piping isn't insulated it would be a good idea to do that before enclosing the ceiling. The energy code is probably going to require the new piping be insulated.

mattmia2

I don't see a purge valve on your system, might want to have whoever does the tie in add that to the near boiler piping so you can block the flow at the boiler and force water in from the prv and out a drain on the return side of the syatem.

Astro64

I had never thought of radiant panels. I'm liking the idea of ceiling hydronic radiant heating as it will be above the boiler and easier to lay out. I'm trying to find a place online that sells them. So far not much luck. My first stop is always Supplyhouse.com but they don't seem to carry anything. Any idea where they can be purchased? The pipes in the ceiling were not insulated but I have been working on that over the last 2 years I owned the house. The basement was actually wide open to the outside air. Don't ask me how they didn't have more pipes burst. I have replaced the hopper windows and bulkhead and installed an exterior door in the foundation at the bulkhead. I also filled all air gaps along the foundation and insulated the joists. I'm about 90% down with wrapping the pipes. On 10 -20 degree days it is staying in the low 50s and that is without walls up with insulation so I'm expecting it to not be too hard to heat when I'm done.

Astro64

Sorry Hot_Rod, I missed the first part of your post. Yes the remainder of the house is fin tube. I have 4 zones of fin tube and 1 zone for my superstor hotwater tank. The fin tube in the rest of the house is from 30 years ago when the house was built. The Burnham Alpine and the pex that is coming from the circulators up to the ceiling is from last fall. The pex is only about 5 feet long and ties into the copper that goes throughout the house.

hot_rod

Depends on how handy you are. Most build their own ceiling or wall panels. Purchase the aluminum transfer plates an Pex tube screw it up against the framing

Find some examples and output info here

https://www.caleffi.com/sites/default/files/file/idronics_25_na.pdf

pecmsg

Do you have extra height to get at least 2" of insulation on the floor and 1/2" Radiant tubing?

Astro64

I have good height to the joists (7ft 10") but I have an exterior door that has pre-formed concrete steps outside it and a bulk head and it doesn't have extra height or ability to be raised up 2 inches. My biggest concern has been dealing with baseboard heat that is below the boiler and will require 2 to 5 risers that are just under 8 feet. I'm concerned about being able to purge the system. I could run it so that I only need to have 2 risers up to the joists but that will require me to run all the connecting copper pipes thru the walls. So, I'm thinking I have a few options. I can run all the piping thru the walls to reduce the rises, I can do as Matt suggested previously and drop down to each baseboard or I can use ceiling radiant panels which would be above the boiler but will probably require me to build my own.

hot_rod

it is certainly possible to have up and down piping in hydronics. Once it is purged and with a good properly placed micro bubble air separator it should run trouble free. Some installers will add auto air vents at high points for extra piece of mine but it should not need that on every "up and over" piping detail.

Home run piping is another good option, usually 1/2 pex to each fin tube or panel radiator.

There are pre built radiators for ceilings or drop in hydronic panels for dropped ceiling grids, but the cost vs building your own would be the trade off.

pecmsg

Depending on your location the floor will always be cool. With little children that's an issue!

hot_rod

The beauty of radiant heat transfer is it travels in all directions, at the speed of light, just like energy from the sun. Anything in it's "sight" will be warmed if there is a ∆T.

Radiant floor would be my first choice as you have conduction transfer, the objects or people in contact.

Radiant ceilings and or walls can be as comfortable, and often easier to retrofit.

Fin tube is convection only, warming the air currents to warm the room, it will not warm the slab.

Panel rads are both radiant and convection, so any body in line of sight gets warmed.

Astro64

Thank you everyone for the outstanding information! I have a few more questions if you all don't mind. My only knowledge of radiators is from when I was a kid we had those cast iron radiators in every room with the bleeder valves on them to get the air out. We use to love putting our wet mittens and socks on them to dry. Those always worked great but did get very hot to the touch but I believe they were steam. If I were to install panel radiators on the walls similar to figure 5-13 that hot_rod posted, would they get too hot to the touch as they will have about 150 degree water going thru them? I like the idea that they would be radiant and convection. My system was built with one extra port on the feed and return manifolds. If I put a radiant panel in each living space, I would need to add another manifold for 8 feeds and 8 returns. I'm wondering how the RTVs will integrate into my system as it only has 1 connection left in the control panel for one circulator/thermostat. Do the TRVs talk to the new manifold and tell it which port needs heat and requests the boiler and circulator to send heat?

mattmia2

The TRV is integral to the panel radiator. The valve comes as stock as part of the radiator and you can put a thermostatic actuator on it. There are a number of ways you can plumb the radiators such that there is a bypass when the TRV is closed ranging from a home run for each to a manifold to separate supply and return mains to in series with a vale that connects them to the loop with a variable bypass.

If you feed them from their own separate manifold and you size them for a lower average temp you could mix the water down to a lower temp in that manifold. That would probably be unnecessarily complex and when you reduce the average temp below 140 or so (for design conditions) the radiators tend to get very large.

With 150 degree water they would be hot enough you wouldn't want to hold your skin against them for an extended period but they wouldn't be nearly as hot as a steam radiator fed with 212 or so degree steam. You can put your hand on the piping while the system is running, the radiators will be virtually the same temp.

Astro64

Good morning everyone. Hot_rod, you mentioned that with a good properly placed micro bubble air separator it should run trouble free. You also said some installers will add auto air vents at high points. I am thinking of installing the Bell & Gossett EASB-JR Air Separator at the top of the 3 places where I will be going up to the joists for my runs. One of those 3 places is at the boiler to go into the return manifold so I'm not really sure it is needed there as I will have a purge valve similar to what exists on the other zones in my system pics I posted. Are these a good product and will installing 3 help ensure a trouble free system?

hot_rod

Here is a good read on how efficient air separation is handled with todays technology.

The two best places to remove air is at the hottest point, right at the boiler, and the lowest pressure, the highest point in the system.

On chilled water systems the air scrubber goes on the return piping

In most cases a good air sep at the boiler and some manual or float vents at high points.

Some installers prefer a manual bleeder on ever fin tube baseboard to speed purging.

When all the flow eventually gets back to the micro bubble device it should clear the system of all air within an hour or so.

Problematic systems, or systems with low pressure, lots of ups and downs may benefit from additional auto vents.

Keeping in mind all vents have the potential to stick or leak at some point due to crud in the fluid or wear, so use caution when scattering them among finished spaces where a leak will cause damage. Safety caps are available as well as an adapter to route the discharge tom a safe location.

https://www.caleffi.com/sites/default/files/coll_attach_file/idronics_15_na.pdf

mattmia2

It already has a microbubble scrubber at the boiler, you can see it in one of the pics, that should be all that is needed for that. Auto valves at the high points are optional, it is very likely purging and possibly bleeding the radiators themselves depending on type will be enough. A few bleeders at high spots just in case is a good idea but automatic air vents are probably overkill.

hot_rod

It is also a good idea to confirm the air sep is actually working. Small discharge ports can plug or the float inside can hang up and render them useless.

Some brands are easier than others to disassemble, confirm smooth operation, clean and reassemble.

The sep you have should do the heavy lifting.