Best way to add hydronic BTUs to cold rooms with limited wall space?

Jells

I've got a 450 sq ft rental in a 100+ year old uninsulated brick building that is heated by the domestic hot water heater. It's been fine for 6 years now, and 3 other similar units have no complaints, but a combination of new tenant and record low temps is causing a cool apt and hysteria. Seems to me the problem isn't the heater btu's but the transfer efficiency. The return line is still very hot. I've looked at some of the flat panel radiators that can double the btu's in a room. The living room has 8' of baseboard with 340 btu/ft @140, so 2720 btu's. A Runtal 17"w x 72"h panel will give another 2500. I figure if that makes the room hot vs the room with the thermostat they can just close the vents on the baseboard.

Any analysis and suggestions welcome, but please let's not get into the cons of heating using a tank. If you'd like to link to other small solutions for heat/dhw I will take a look. I have a legacy flue but direct venting there is very difficult.

hot_rod

it is always wise to do a load calc first to be sure you are adding enough heat emitter.

a quick inexpensive addition would be a kicks space heater or cabinet model.


https://smithsep.com/products/quiet-one-kickspace-heaters/

Jells

I had looked at kickspace models, it would be tricky to install, I'd have to put it like vertically in a closet and wall it off, and it would give roughly the same btu's as the wall radiator.

hot_rod

Typically you get a lot more output from a forced convector, adding a small fan to a finned convector.

Here is an output chart.

NY_Rob

How about something like this... only 28" wide and 8,700 BTU's...
http://www.htproducts.com/fan-coil.html

Jells

Rob, thats an interesting unit. Any idea what they retail for? I cant find an online vendor.

Paul48

Or Smith's version https://smithsep.com/products/profile-fan-convector/

bob eck

Two copper baseboards that work on lower water temps

BTU at 140 degrees

Heating Edge copper baseboard
626 btu foot 4 GPM
www.smithsep.com

Sterling Synergy copper baseboard
502 btu foot 4 GPM
www.sterlingbaseboard.com

HVACNUT

How many rooms? 1BR, kitchen/living room combo?
How about a ductless system?

Jells

Boy is getting info from HTP a fustercluck. They sent me down 3 levels of distributors to someone who couldn't even find the model in his listings, never mind give a price. I'm working my way through Smith's offerings.

Bob, that's also interesting. Basically double the output from the heating edge!

NY_Rob

Jells said:

Rob, thats an interesting unit. Any idea what they retail for? I cant find an online vendor.

https://www.homedepot.com/p/Westinghouse-43-in-Ultra-Thin-19600-BTUH-Glass-Hydronic-Baseboard-Heater-VFC-20GWV/301174197?cm_mmc=Shopping|THD|G|0|G-BASE-PLA-D26P-AirCirculation|&gclid=CjwKCAiAhMLSBRBJEiwAlFrsTmnrssUXjDVey7MbeDGVTUFqQ0xMVoZoM4YeHDyFuhplkVoL4bmBrRoCB_sQAvD_BwE&gclsrc=aw.ds&dclid=COrF7-qQxNgCFZO4yAodUh0Gvg


https://www.amazon.com/dp/B01MT1RKDO/ref=asc_df_B01MT1RKDO5327445/?tag=hyprod-20&creative=394997&creativeASIN=B01MT1RKDO&linkCode=df0&hvadid=225413556214&hvpos=1o2&hvnetw=g&hvrand=11513962728072988737&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9004491&hvtargid=pla-390193317343&th=1

mikeg2015

Huh. I once emailed them and got a fairly quick response from a technical person. I was asking about maximum delta t and minimum flow rates.

That was 2 years ago.

Jells

Rob, unfortunately I don't have room under the windows in for that in the room with the least baseboard, the window apron molding is at 19". I think a wall next to the heater closet is 42 or so wide, and on the side of the closet I have about 28 to work with. In the other room I have more flexibility, although I don't know what the effects of constricting the flow to 1/2" from 3/4" out in the middle of the loop will be. I'd like to see the price on the downscale metal version instead of this "iRad".

Is the Westinghouse a rebadged HTP, or just very similar?

Jells

What do you guys think of this kickspace heater with a surface mount box? It says 4770 btu at 130 and 1 gpm. That should be more than enough! And at least from SupplyHouse I don't have to deal with the distributor and special order nonsense.

https://www.supplyhouse.com/Beacon-Morris-K84-K84-Kick-Space-Heater-4772000-p
https://www.supplyhouse.com/Beacon-Morris-F84-F84-Surface-Mount-Cabinet-Kit-9767000-p

Is there a way to have these units only kick on the fan if the passive baseboard isn't keeping up? And how do I calculate the gpm for a Taco 007 on a 3/4 loop with no constrictions but 2 of these 1/2" units?

One more question I guess I should have started with: does a 40 gal plain vanilla water heater truly have the BTUs for this? I just looked at the Rheem line, I think it has 40k btu. The place currently has about 28' of 340 btu/ft@140 baseboard, so 9520 total. This is the 1st time in 6 years it's been operating that there's been a complaint.

hot_rod

When you look at water heater ratings, that input BTU rating needs to be adjusted for efficiency.

Perhaps a 75- 78% efficiency for a standard vented HW tank. 40,000 X 78%= 31,2000 BTU/hr. And altitude derate if applicable.

But you do not have near enough heat emitter to transfer that output to the space.

Kick space fans typically turn on via a temperature snap disc control. Some have choices of temperature, so the copper tube inside would need to rise to say 140 to kick on the blower.

If you want it to kick on with decreasing room temperature, that would take another thermostat, or a two stage.

The un-insulated brick walls are not your friend

Now a days we expect to heat that sq footage with MAYBE 6- 7000 BTU/ hr. Possibly even 10 BTU/ sq ft on a super insulated, tight structure.

Are you supplying 140F to the baseboard? You need to know the average temperature through the fin tube not input.

140 in, 120 return for example 140 plus 120 divided by 2 is 130 average, look at the board output at that temperature.

Increasing the pump flow will decrease the delta and increase the baseboard output a bit, speed the pump until is starts to get velocity noise and back off a bit. No need to worry about short cycling with a 40 gallon tank.

And one more thing... you don't want to run a non con tank type heater below 120 for extended periods, if you drop below the fuel dew point it may be condensing inside and rust/ rot the flue piping and burner.

NY_Rob

Jells said:

Is the Westinghouse a rebadged HTP, or just very similar?

It's a rebadged HTP product (which HTP probably imports BTW).

Same goes for the Westinghouse Mod-Con boilers you can purchase online. They are simply rebranded HTP UFT boilers (which HTP imports from Korea and "finishes" here- whatever that means).

Jack

450 sq ft? Install a Rinnai EX-11T in natural or propane. Sub meter the gas side and let the tenant pay for it. The 11 will modulate on the burner and fan from 5500-11000 btu. Programmable stat built in, easy install, 2.5" hole for the sealed combustion vent. Very durable and reliable. 9" vent clearance to a door or window. Quiet, cool to the touch and a discreet max tamp setting for a landlord so you get to pick the high setting if you choose to not sub-meter.

Jells

Thanks Hot Rod. Can the flow be changed on the Taco 007? What instrument is best to monitor i/o temps? Do I need to be concerned about the loop CV added by the 1/2" devices at all? CV on baseboard loops has always been mysterious to me since I solved my "problem" with my own indirect tank's slow recovery by replacing the Honeywell zone valve, with it's tiny port, with a full port W-R.

Jack, like I said in the OP direct vent is not an easy option. I'd need to run the pipes up the flue to the roof. FWIW tenants have their own meters.

NY_Rob

Many of us use this to monitor supply/return temps...

http://www.houseneeds.com/heating/hydronic-heat-supplies/azel-digital-temperature-gauge-sensor-probes-ds-60p

Jells

Thanks Rob, always good to have an excuse to buy new toys! Though I'd be more impressed if it could log temp readings like my little lipstick thermometer. Downloads datasets & graphs right to your PC so you can see the rise and fall during a heating cycle, a nice sine wave.

NY_Rob

^ Did you say data logger for the same price

https://www.ebay.com/itm/4CH-RTC-Temperature-Data-Logger-Recorder-55-125-C-Bluetooth-DS18B20-/122498213430?_trksid=p2385738.m4383.l4275.c10

and $5 BT module for Android:

https://www.ebay.com/itm/152706541172

Jells

Hah! That's pretty cool, but it looks like learning to use it and output data to graphs using standard software would make it a time consuming hobby before it was a real productivity tool. If I were a pro it would be a no brainer, as is I manage 10 heating systems, one of which is steam, and only one hydronic is causing me trouble.

I have one more 450 ft unit to install a modern system in, and I'm now thinking forget the damn fugly and bulky baseboard and just go with one of these blower units in the 2 major rooms. I know custom calls for heaters under the windows to intercept drafts, but you can't have everything.

MPott

Did you find a solution to your problem? Did you end up getting more details or ever using the Fan Coil unit from HTP?

Jells

MPott said:

Did you find a solution to your problem? Did you end up getting more details or ever using the Fan Coil unit from HTP?

Funny you should revive this, the last unit I have that needs a system installed is coming vacant at the end of the month! I ended up installing 2 of the Beacon Morris fan/coil units in surface mount cases. Then after all the effort and expense the tenant who was such a PITA moved out breaking her lease. Good riddance. The tenant since said it got a little cold, but was not bad. I should put a logging thermometer in there and see what's really going on. Found great ones recently on Amazon, 2 for $18. https://www.amazon.com/gp/product/B08CGM8DC7

So now I have to build from scratch and decide the best approach. A Mod-con is still not a good option due to venting issues. Damn, all the numbers I researched on this have evaporated from my head! I need to dive again into the relative BTUs from the water heater vs radiant capacity of the baseboard options.