Panel radiator in baseboard loop

nj6964

First poster here, please pardon any etiquette breeches.
I currently have a steam system with a boiler about to die. I'm going to convert to hot water heat in my 2 story old colonial with the help of my father, a plumber/inspector of 35 years who installed almost exclusively hwbb loops in his day.

He's suggesting installing all tube/fin hwbb. I have 2 rooms where I just installed beautiful tall baseboard trim last year and I'd really hate to lose it so I want to try and use a panel radiator in those rooms.

My question is how can I run a single loop around my first floor and include 2 panel rads? I've looked at different options like monoflo tees, etc. I'm not deadset on using a TRV. I've heard these panel rads have fairly low restriction to flow but they are 1/2 and I'll be running 3/4" hwbb. Can I plumb the rad in a series loop with a 1/2" bypass line to compensate for the lost flow? I really prefer to keep the piping as simple as possible because I'm asking a lot to get my dad to invest 2-3 entire weekends to do this job and I don't want it to drag out. Not to mention I'll be without heat the entire time (luckily we have a wood stove).

JohnNY

Monoflow tees aren't a terrible idea.
You could also do something like this, but as you seem to know, mixing heat emitter types is not ideal:

nj6964

Thanks for the quick response. That may be a good option for me. I just wish the 2 rads we closer together. If I use monoflow tees with a 3/4" main can I just overcome head loss with a bigger circ pump? The first floor will have about 30' of hwbb (~18000 btu) one 8000 btu rad and one 5000 if that helps. I have my pops coming over today to help make up the shopping list.

JohnNY

Yes, you can. Chances are pretty good that a Taco 007 takes care of the flow you need, but I often find a 0010 brings me closer to my 20°F temperature differential from boiler outlet to inlet when using a lot of fin-tube.
Not that 30' is a lot.
Don't overthink this.
You'll be fine.

nj6964

Thanks so much John. How much truth is there that these euro style panel rads aren't meant to be run on a monflow system like the old cast iron hot water rads from the 1950s? Are they really that different? I guess if you're saying you've done panel rads before that works for me.

Also does the taco 007 pump replace the main circulator or is it added just to the loop that has the rads as a second circ pump?

JohnNY

There may be some truth to the panel rads not being "meant" for a 1-pipe monoflo system but that doesn't mean they won't work.
To work well, the monoflo tees generally require very little resistance to flow through the "bull" (as opposed to the "run") of the tee. A wide open cast iron radiator is better for that, sure, but I wouldn't let that stop me from connecting a panel rad to the loop. I can't recall evert doing it, but I'd certainly try it and feel fine about it.

As for the pump, I can't speak to your system without having more information.
Post a wide pic of your boiler if you'd like. Others will chime in too.

nj6964

Great to know. I don't have the boiler yet because it's going to be new. I'm replacing an old steam system. Now that you mention how monoflow tees prefer a wide open cast iron rad, I'm slightly concerned that this setup might not work.

I'm envisioning the 1st floor zone as 3/4" supply going to 6' of hwbb in kitchen, then to a 5k btu double double panel rad with monoflow on return side. Then to 25' of hwbb then to a 8k btu dd panel rad also with monoflow on return side. I plan on having 3 zones: 1st floor (w rads) 2nd floor (all hwbb) and hot water storage tank. We decided today to use a taco 010 pump. Boiler will be WM CGA 140k btu.

I guess I'd feel much better if someone has used monoflow tees with panel rads in the past and how it worked out. I'd hate to do this and not have it work. Is 1 mono tee on the return sufficient or should I need 2 mono tees? Any advice is tremendously appreciated.

KC_Jones

nj6964 said:

Boiler will be WM CGA 140k btu.

Have you already done a room by room heat loss calculation to size the radiation as well as the boiler? That's a fairly large boiler for a typical residential application.

Also I have to ask, why are you tearing out the steam?

nj6964

Hi KC, yes my dad's friend still installs he systems and he ran some numbers that we need 120k btu for the whole house. The 2nd floor has 36' of element and 32' just cover. We're also making domestic hot water with the boiler and planning to finish the basement someday.

We're ditching the steam to get rid of the low hanging pipes in our already low basement. Also it'll be nice to be rid of that banging sound (though I know that could be fixed if someone tried hard enough).

ChrisJ

The banging can be fixed very easily. It takes very little effort by someone that knows how to work with steam.

JohnNY

I'm also concerned about the size of that boiler. You're talking about 2 loops of ¾" piping, right?
You described 31,000 installed BTUs in total. Where does a 140,000-BTU boiler come into play?
You should do some more figuring for your dad before you get him to install.

KC_Jones

To output 120k BTU you would need roughly 200' of baseboard at 180° water temperature. The domestic hot water doesn't usually factor into the boiler sizing. Boilers are sized by the heat loss of the building, not how much emitter you have.

JohnNY

nj6964 said:

The 2nd floor has 36' of element and 32' just cover.

That's about 21,000 BTUs. If you're using an indirect, the system should be wired to isolate the functions of heating and domestic hot water.

Either way, your boiler sounds oversized by about 100%.

nj6964

Hmm I guess I didn't dig deep enough maybe. So between 1st and 2nd floors I'm getting roughly 55k btu output. Does the efficiency of the boiler come into play? 140k boiler at 85% = 120k btu output. My current steam boiler is 150k btu if that helps.

Rookie question but what happens if the boiler is oversized? Thanks for all the help.

ChrisJ

Well,
An oversized boiler costs more.
It's heavier and physically larger.
It's going to short cycle constantly which will eat fuel.

It's bad bad bad.

Do a proper heat loss and figure out the proper amount of radiation you need and buy the right size boiler.

nj6964

Ok I definitely will. I revisited this and my dad is saying "yeah maybe that's oversized".

Regarding the 2 panel rads and monoflow tees. Any doubts it'll work? I see several place that list I think as a recommended method for them but I'd hate to be wrong.

Bob Bona_4

You'll be fine with one monoflo T per panel rad. Be sure you have the correct orientation to flow.

You really ought to be installing a modulating condensing boiler, something like 55K, 85K on the high end, for domestic hot water. Then it can modulate down for your bb zones, a closer match. Take into consideration your chimney liner, if you are sticking in an atmospheric boiler. The relining cost cancels out the cost of a modcon, they can be direct vented.

nj6964

Thanks Bob! I'll definitely look into that. How many many panel rads do you think could go on a 3/4" loop zone with monoflows? Going to be using taco 010. For example I'm currently going to be putting 9k and 5k btu rads + ~ 30' hwbb. I'm worried if instead of the 21' of hwbb in my family room I use a 12k btu rad that it'll add too much head loss because normally monoflow systems use 1 1/4" pipe. Thanks again!

Brewbeer

Hi @nj6964, I installed a totally new hot water baseboard system for my house last year. If you are seriously considering a low temperature system to fully utilize the condensing aspect of a mod/con boiler, you should take a look at my thread where I and the helpful folks here on The Wall went through the design thought process for my house. Thread link is in my signature.

I agree with the folks recommending a room by room heat loss calculation. It really is the foundation of a comfortable and efficient heating system. I also agree with the others that a 140K BTU boiler is probably more than double than what you will actually need. For example, my house (2000 sq.ft. split ranch built in 1965) only needs about 30K BTU when it is 0F outside.

Starting this project kinda late in the season, eh?

njtommy

@Brewbeer nah Nj winters generally warm till January or February. His got 4-6 weeks till I would be worried. It's in the 30s-40s in the nights and 60s still during the day.

Bob Bona_4

0010 is a fine pump. I'd lean towards a Viridian 1816 tho. Gives you a little more flexibility, energy savings, and if you ever TRV the panel rads it's a good match.

nj6964

Yeah timing is less than ideal, boilers never Leak at the right time. I'm in northern NJ and my heat's been on most days for the past month.

What is the thought on if a 3/4" supply is sufficiently large to add a 3rd rad on monoflow, to this floor instead of 25' hwbb?

Thanks to everyone for all the advice. I'll follow up with how it went.

nj6964

Also I just checked out the vr1816 pump. It looks like it can handle twice the max head 18 vs 10 (with 0010). It's variable and uses less power. I must be missing something but for the same money why wouldn't everyone get this pump? Is it also much stronger than the 007, which I've been told may be too weak for my system. Thanks!

nj6964

I ordered the 2 panels rads from hydronic alternatives and their customer service was exceptional. They did mention that they always recommend 2 monoflow tees per radiator. I mentioned I saw most places saying 1 only on the return, they said to use 2. Any thoughts?

What are the risks if I use 2 when I may have only needed 1 or vice versa?

ChrisJ

njtommy said:

@Brewbeer nah Nj winters generally warm till January or February. His got 4-6 weeks till I would be worried. It's in the 30s-40s in the nights and 60s still during the day.

Depends on the area.
We've had mid 20's at night a few times and all we need is a cold snap which often happens in November and December.

njtommy

@ChrisJ key word is Generally. Lol.

For anyone that doesn't know North Jersey is a different state then South Jersey.

Paul48

I think we need to back up to your original post. Using monoflow tees for a first floor application, designed from scratch, doesn't make any sense. With PEX available, it's not saving any labor.

njtommy

I would look into running a direct pipe system from a manifold. Like Paul Said pex is cheap and easy to pull.

Mark Eatherton

FWIW, I have 4 Buderus panel radiators on a 3/4" line with two venturi tees (not the same as a Monoflo pressure drop wise) and they work fantastic. I'm only running a Grundfos 1542 for that loop. I also heat my bath tub, a towel warmer and a 3 section LeFleur cast iron radiator on the same loop, with no problems. I also have TRV's on all the panel rads so I can zone each room individually.

If you run the panel rads in series with the BBR loop, you can't use TRV's. If you do the homerun system using PEX as recommended, you could use TRV;s through out except for the "reference" zone where the thermostat would be located.

ME

nj6964

Quick update, we got the boiler in and the first floor zone running. We plumbed the 2 panel rads with 2 Venturi tees each and they're working great so far. The rads get hot really fast, right now because I have them running wide open (no TRV or manual valve). I'll probably need to modulate them with a valve if they heat up faster than the other rooms' baseboard, we shall see. Tomorrow is running the 2nd floor baseboard loop and voila! Thanks for all the help.