Need help sizing my hydronic baseboards

mrflip99

Hi All,

I'm planning on converting this 1st floor 1000sqft unit from steam to hot water baseboard. This is my first rodeo with hot water baseboard so bit of a newbie. I'm more familiar with steam. Ceiling height is standard. See attached floor plan for more info. I plan on making the sunroom a bedroom.

- What size baseboards should I get for each room? I tried calculating this myself but got lost at taking account for heat loss. Its an older home so I would say its middle of the road insulated.
- Is series circuit or one-pipe w/TRVs better setup? Would it make a difference for this smallish unit being only 1 floor? I'm ok with either but keeping a low budget is priority.
- Any other considerations I should keep in mind when building this system out?

hot_rod

You really need a room by room calc to size the emitters. That sunroom for example with glass and two outside walls will have a higher load than the bedroom with less glass and exposed wall.
Try this. https://www.slantfin.com/slantfin-heat-loss-calculator/

Then decide if you want individual zones for various rooms. TRVs are nice, but mounted on the baseboard is not my favorite method

mrflip99

Thanks for link bob! Super helpful!  

Is there a reason why TRVs on baseboards aren’t recommended?  I plan on single zone but worried about not evenly heating the house as it’s my first year in it - not sure which rooms are colder than others.  How can I mitigate this and have flexibility once the system is in?

Hot_water_fan

Why not wait to see how the steam does and if it’s adequate, size the baseboards off of that? Ie find the steam output (assuming it’s distributed well) and match it with hot water baseboard. Or keep the steam and save the most money

hot_rod

mrflip99 said:

Thanks for link bob! Super helpful!  

Is there a reason why TRVs on baseboards aren’t recommended?  I plan on single zone but worried about not evenly heating the house as it’s my first year in it - not sure which rooms are colder than others.  How can I mitigate this and have flexibility once the system is in?

You can adjust output of fin tube baseboard somewhat by adjusting dampers.
Also the way you supply them will have make a difference on output in a series loop

The load calc will indicate rooms with the highest loads. Use adequate baseboard to cover the load in every room, fine tune or setback unused rooms by regulating dampers.

consider the design around 150- 160 supply to run a cooler more efficient boiler

A boiler protection valve would allow lower SWT if you use a non condensing boiler

Jamie Hall

At some risk of sounding like an idiot, is there some reason why you are not just adding hot water baseboard loops for the new spaces, powered by the steam boiler, and just keeping the steam for the rest of it?

mrflip99

My goal is to have this done before it gets cold.  Another reason I’m doing it is to separate out the heat, it’s two units and only one heating system.

Bob - what do you mean by “the way you supply them?”  Are you referring to insulating the pex?

hot_rod

mrflip99 said:

My goal is to have this done before it gets cold.  Another reason I’m doing it is to separate out the heat, it’s two units and only one heating system.

Bob - what do you mean by “the way you supply them?”  Are you referring to insulating the pex?

The order in which you supply them. The very first one sees the hottest water, as you go to the next, and further around the all see lower water temperature. So sometimes you can plan to send the supply to the rooms with the highest load, first on the loop.

sometimes splitting into two loops also helps with higher supply and better output, still a single zone system but split 70’ into two 35’ loops

EdTheHeaterMan

Since you are going to basically be starting from scratch with a new small boiler and a complete baseboard layout, you may want to look at this booklet. Lots of info and easy to understand. zoning baseboard with TRV starts on page 20 http://media.blueridgecompany.com/documents/ZoningMadeEasy.pdf. but you want to steer clear of MonoFlow type systems for zoning. The kitchen may need to have the interior wall used for the baseboard, or you could use a Kick-space heating unit like this under the cabinets that are on the outside wall.
Since that will reduce the pipe size to 1/2" You can make home runs back to the boiler room or you can add a bypass and valve in order to increase the water flow up to the 4 GPM required to provide enough water flow for the load.

Here is a mock up of the lowest cost design for your project.
Start at the boiler with 3/4" copper and go in series to each baseboard, around the home until you get to the last radiator and return to the boiler.

This will work if your total load is less than 40,000 BTUh. ...and I believe it will.

EdTheHeaterMan

If you have a load greater than 40,000 BTUh, then you will need to split in to 2 loops with a 1" supply and return, that branches off to the two 3/4" loops. But I don't believe your load should be over 40,000 BTUh. Now if you are planning on removing most of the windows from the sunroom in order to make it a bedroom, then you can just continue the series loop to that room and use one thermostat for the first floor. Adjusting rooms that get too hot can be done by the Dampers on the baseboard radiators.

Properly designed with the load calculation as your guide, you will have a well balanced system

Mr. Ed

hot_rod

Another option is panel radiators with a pex home run piping. Once you have a room by room load price out both options, copper fin tube vs panels.
Panels are a bit more durable, a nicer heat feel , mostly radiant and very easy to zone each one.

10' of 3/4 fin tube gets you about 5000 btu/hr. or a 16X36" 2 pass panel rad about the same output.

TRVs could be added at a later date if you want more than the manual balance they come with. In many cases two, sometimes 3 can be in series to eliminate as many runs back to the manifold.

I have not installed a fin tube job inn years, last I remember the metal enclosures were getting pretty thin and "dent-able" maybe get a sample piece to see if you are okay with that type of emitter.

mrflip99

Edtheheaterman - thanks a bunch for the heating diagram, super helpful!  Same with the pdf, real eye opening.

- the total BTUs come out to about 20k through the Slant/fin calculator.  Does this mean I need a boiler of 20k BTUs or do I oversized by a certain percentage?

- When searching for boilers, should I be looking at BTU OUTPUT, IBR rating or DOE rating to compare against my 20k need?
- is there a downside to do 2 loops, single zone when below 40k btu heat loss?  is there a fear of short cycling / bad for the boiler?

hot rod - I probably will steer clear of the panel radiators due to high cost in comparison to slant fin baseboard.  I do appreciate the suggestion as I did r know those existed!

GGross

I really wish the panel rads would catch on in my area. I put them in a few places at my house and the heat is great, closer to an old school radiator in the way it feels than a piece of baseboard. I just can't get anyone to try them out. If I were building new and couldn't budget for in floor, my next choice would be panel radiators for sure

mrflip99

@EdTheHeaterMan @hot_rod - a bit off topic, but related, I just received the following email from PSEG regarding adding a 2nd meter:

"EXISTING 1" PS U.P. SERVICE IS MAXED OUT ON CAPACITY. IT WILL NEED TO BE
ENLARGED TO 2" PL U.P. FROM MAIN TO 44' INWARD TOWARDS HOUSE. WE WILL
THEN TIE BACK INTO EXISTING 1" PS U.P. GOING INTO HOUSE. CUSTOMER ALSO
REQUIRES A 425 METER. CONTACT METER DEPT. @ 973-414-1574. 4" W.C. IS ALL
WE GUARANTEE! THE COST IS 500.00 PERMIT FEE. PERMIT WAIT TIME 10 DAYS
FROM SUBMITTAL."

- Correct me if I"m wrong but It seems like the existing line/branch that supports the houses on my block, is inadequate for my additional load.
- This line is not the same as the 1" line that goes into my house. The 1" line into my house is adequate.
- Are they allowed to pass on the $500 Road Opening permit fee to the home owner? It seems like the line they need to upgrade is the line THEY are responsible for and should be the ones paying for the road opening permit. (similar to a water main, I'm responsible for the line that comes into the house up to the "construction stop" which connects to the line that supports all the houses on the street.)
- if i'm right about this, who do I speak with to get this rectified?

EdTheHeaterMan

mrflip99 said:

Edtheheaterman - thanks a bunch for the heating diagram, super helpful!  Same with the pdf, real eye opening.

- the total BTUs come out to about 20k through the Slant/fin calculator.  Does this mean I need a boiler of 20k BTUs

There are three ratings on a boiler,
Input in BTUh, this is used to size the gas pipe to the appliance
Output, in BTUh this is used to compare efficiency with other heating appliances like furnaces
NET in BTUh formerly know as I=B=R NET but today it is NET AHRI. This is used to match the heat loss calculation. So you need a boiler with a NET rating of at least 21,000 BTUh but I don't believe there is a boiler made the is that small. So what ever boiler you get will be large enough. A boiler like Velocity Boiler Works AWR038B or Weil McLain CGa 2.5 will be the smallest with a rating of 32,000 AHRI NET.

As far as the gas company is concerned, you can try to tell them that there are no additional appliances going into the building. You are just splitting the existing gas ranges, water heaters and clothes dryers so the tenant will pay for their own gas usage. Give as little info as possible, Don't volunteer additional info. In fact you can say that the heating boilers combined you are going to install are smaller than the one big one you are removing. even if you are not removing the steam boiler for 20 or 30 years from now. LOL

So call the Gas Company and ask for someone in management who can override the engineer who made the determination that the street needs to be dug up. (How come you need to make a bigger gas main in the street when the net result of the project will use less gas?) It sounds like they are using your small gas saving project to justify getting someone else (YOU) to pay for their need to upgrade the infrastructure used by the entire street of customers past your house. Does your Public Utility Commission know that you are unfairly charging consumers for this type of work?

It may work, it may not. But if you don't ask they can't say no. They tried it on you, by asking for $500.00. If you said OK then it is over and they saved $500.00 on a street opening permit. Now it's your turn

mattmia2

This could be a situation where the main is only 7 in or so. Sounds like they are enlarging the service to a certain point to reduce the pressure drop on the service.

mrflip99

@mattmia2 what makes you think it is 7" when their statement says its 1"? just curious if you have inside information or prior experience? Is it normal to pass the bill to the customer for this type of work?

Jamie Hall

mrflip99 said:

@mattmia2 what makes you think it is 7" when their statement says its 1"? just curious if you have inside information or prior experience? Is it normal to pass the bill to the customer for this type of work?

1 inch is the line going into the house; they didn't include any information on the size of the main -- but @mattmia2 's figure isn't a bad guess.

And yes, it is quite normal for the company to charge the customer for adding or modifying a service -- and it makes sense, since the only one benefiting is the customer.

mattmia2

i'm talking 7 in water column pressure at the main so the service needs to be sized like the premises system to keep the pressure drop low vs a more modern system where the main is 2 psig or more and there is a regulator at the meter.

mrflip99

Spoke to the inspector, he stated that what is currently in place is causing my gas firing appliances to run inefficiently - similar to a dirty carburetor.  That was his only way to understand it and myself not being well versed in plumbing took it for face value.  I also noticed that other utility companies also pass the cost of the permit to the customer.  They will also be modifying the 1” service line that goes into my house.  They will shorten the run to 2 feet from the current 10 feet - explained that it will put enough “back pressure” to the gas coming in.  I asked if it will increase the water column (I think this is a measure of pressure) but said it wouldn’t.  I’m open to any further explanations.  I ended up paying the permit so that I can move my project along.  

On another note - what are the pros and cons in using a combi boiler vs a standard hydronic boiler - other than price?  I will be using second hand equipment and found a standard boiler for $600 and a combi unit for $1200 so I wanted to evaluate the differences.  I am aware of the necessity of a chimney for one and direct vent for the other but either will work for my situation.  Is the labor install the same for either? What’s the difference in utility bills with one being more efficient than the other?  Does one have more maintenance involved?

mattmia2

The question is static pressure vs dynamic pressure. I think what they need to do is decrease the pressure drop when all of your appliances are operating by making part of the service larger.

EdTheHeaterMan

I would use the low cost option. The lower cost boiler will have less moving parts and less maintenance issues. it will cost a little more to operate, but is that going to be your cost or the tenant's cost? Since I'm guessing the second meter is so you can split the utility bill with the tenant. Just as a former landlord, the most economical thing for the landlord is the low cost boiler. After that the operating cost is differed to someone else. And the existing chimney for the steam boiler is probably just fine for the less expensive boiler. But that is for the installer to determine... unless that is you as a DIY. We need more info and pictures of the existing system and chimney connection and boiler model numbers for the new(used) boiler, if you need more info on venting and piping the project.

A Combi will need to be replaced long before the standard chimney vented boiler. Are you also separating the domestic hot water (DHW) for the zone? That is another whole piping project. A combi boiler makes both heat and DHW. If you don't separate the DHW properly, you may not legally be able to have someone else pay that gas meter bill if you are getting the DHW in more places than just the zone for that meter.

Rich_49

mrflip99 said:

@EdTheHeaterMan @hot_rod - a bit off topic, but related, I just received the following email from PSEG regarding adding a 2nd meter:

"EXISTING 1" PS U.P. SERVICE IS MAXED OUT ON CAPACITY. IT WILL NEED TO BE
ENLARGED TO 2" PL U.P. FROM MAIN TO 44' INWARD TOWARDS HOUSE. WE WILL
THEN TIE BACK INTO EXISTING 1" PS U.P. GOING INTO HOUSE. CUSTOMER ALSO
REQUIRES A 425 METER. CONTACT METER DEPT. @ 973-414-1574. 4" W.C. IS ALL
WE GUARANTEE! THE COST IS 500.00 PERMIT FEE. PERMIT WAIT TIME 10 DAYS
FROM SUBMITTAL."

- Correct me if I"m wrong but It seems like the existing line/branch that supports the houses on my block, is inadequate for my additional load.
- This line is not the same as the 1" line that goes into my house. The 1" line into my house is adequate.
- Are they allowed to pass on the $500 Road Opening permit fee to the home owner? It seems like the line they need to upgrade is the line THEY are responsible for and should be the ones paying for the road opening permit. (similar to a water main, I'm responsible for the line that comes into the house up to the "construction stop" which connects to the line that supports all the houses on the street.)
- if i'm right about this, who do I speak with to get this rectified?

They do not need to upgrade anything . YOU need them to upgrade it