Runtal Radiator Placement Review/Advice

camp10

Hi guys,
Attached is my planned layout for the runtal radiators in my upstairs living area. I am hoping some of you guys might get a second set of eyes on this layout and point out any mistakes or provide some advise for a first timer. All the radiators are Runtal, and each will be controlled with a TRV and piped via a home-run system. I found that a SWT of 150*F to the radiators is the best compromise for radiator size.

The heat-loss calc was performed by a PE with a design day of 29*F, he came up with 27,537btu for my 1,248 sq/ft house, or 22btu/sq.ft. I plan on installing a Lochinvar Knight KHN055 modcon boiler, a 50 gallon indirect water heater set up to be priority heated, and an 18 gallon buffer tank to deal with the small heating zones. I will circulate the heating water in this system using a delta p variable speed pump controlled by the logic of the boiler. Thanks for any advice.

Sean

Zman

Overall the this looks solid.The location of rad "B" had me scratching my head. What are the limitations on the opposite exterior walls?
I like the buffer tank design.
I am guessing that the heat loss and design temps are a bit conservative (not a bad thing). Absolutely run this with outdoor reset and play around with "how low can you go" on the the design SWT. I bet you can run 130 degrees on the design day and 90 on the warmest. You can play with the settings to optimize efficiency.

camp10

Thanks Zman. The locations of radiators B and C were both a compromise. I preferred to put rad B on the exterior wall, but there is a doubled up 2x8 rim joist where the pex piping penetrations would have to go through the floor below. I am a little uncomfortable cutting the rim joist up to get the pex through, but I am willing to listen to suggestions otherwise. Putting rad B on the exterior wall would also allow me to use a baseboard type radiator, as opposed to the vertical radiator I'm currently looking at.

Boon

Having just finished a similar project my only regret (aka only suggestion to you) is that I didn't give enough consideration to furniture placement. If I could do it again, I'd reposition or reconfigure 3 or 4 of my 17 rads to improve the layouts.

camp10

Thanks Boon, I'll make sure to go over the rad layout plan again with my wife with consideration to furniture placement. I've bookmarked a bunch of your discussions from last year and the system you installed, lots of great information shared.

Boon

Sean, I checked some of your BTU values and I think your numbers still include the 15% heating factor. My apologies if you were aware of this and intended to use the listed ratings as they are.

I was encouraged by many Wallies - directly and indirectly through various threads - to eliminate the 15% heat factor. My own calcs, for example using your 6 tube 4' radiator (G), would further divide 3832 by 1.15, which puts the output at 3331.

I looked for some of those threads now and can't seem to find them. @Zman I'm not making this up, right?! The listed ratings are overstated for some reason.

David

Zman

Boon said:

Sean, I checked some of your BTU values and I think your numbers still include the 15% heating factor. My apologies if you were aware of this and intended to use the listed ratings as they are.



I was encouraged by many Wallies - directly and indirectly through various threads - to eliminate the 15% heat factor. My own calcs, for example using your 6 tube 4' radiator (G), would further divide 3832 by 1.15, which puts the output at 3331.



I looked for some of those threads now and can't seem to find them. @Zman I'm not making this up, right?! The listed ratings are overstated for some reason.



David

The 15% pickup has been mentioned on here from time to time. I don't remember it in regards to the Runtals but it may well apply.
As I mentioned earlier, the important part is to be sure your sizing is balanced to the load on a room to room basis. If in fact, as I suspect, the radiators are a bit oversized to the load, you can adjust the heating curve accordingly.

Boon offers some good advise on placement of furniture. The majority of the heat from the rads is radiant rather than convective, especially at the lower water temps. Be careful not to block them.

Alan (California Radiant) Forbes

I always thought that the majority of heat from finned Runtal radiators was convective, not radiant and that only the un-finned Runtals were radiant.

camp10

Boon said:

Sean, I checked some of your BTU values and I think your numbers still include the 15% heating factor. My apologies if you were aware of this and intended to use the listed ratings as they are.



I was encouraged by many Wallies - directly and indirectly through various threads - to eliminate the 15% heat factor. My own calcs, for example using your 6 tube 4' radiator (G), would further divide 3832 by 1.15, which puts the output at 3331.



I looked for some of those threads now and can't seem to find them. @Zman I'm not making this up, right?! The listed ratings are overstated for some reason.



David

Hmmm, I just did a little digging on Runtal's website and found that they suggest using the 15% heat effect for placement along outside walls with some of there commercial type radiators. This is news to me thanks, for pointing that out. I sent a question via email to Runtal, and hope to hear back from them if this applies to their residential type radiators as well.

Boon

Yea it took a while to find but Runtal does include the added "15% heat effect" in their output charts. Here is the link for anyone listening in:
www.runtalnorthamerica.com/commercial_institutional/type_r_heating_cap.html

Even though the added 15% is listed under the commercial charts, those commercial charts show the same output values as the residential types. So I'm pretty sure the 15% was also added to the residential charts.

Based on your reply I'm thinking you didn't realize that some of your radiator sizes match up with the R-type commercial radiators. The in-stock UF type radiators, the ones you'll probably want to order, don't come 1, 5, or 7 tube configurations. If you order the UF in-stock ones you'll need to bump those tube configs to 2, 6, and 8 and/or fiddle with the lengths, of course.

The R type commercial ones look just the UF series so it is easy to get them confused. Best I can tell, the only differences between the residential and commercial is that you can specify custom piping on the commercial and you can specify the commercial ones to be rated at higher pressures.

For lead time you might want to stick to the UF series unless you're set on the 5 and 7 tube configurations. I had to special order three same-side piping radiators and they took like 5 weeks to ship. I don't think the cost was all that much more, if any, than the in-stock stuff.

camp10

Up until this point I had not paid any attention to the commercial type radiator Runtal offers. Thanks for noting the charts in the commercial section will cross reference with the residential radiators. I'll run the numbers again and make sure the sizing is balanced to the load of each room like Zman mentioned above.

And thanks for the heads up on the ordering lead times, I need to get my selections finalized and put my order in.

Alan (California Radiant) Forbes

I never use the UF (in-stock) radiators because they come with side and bottom tappings; plug the ones you don't use which looks ugly to me.
I like the customizable R, RF, R2F and R3F commercial radiators where you have to specify tapping locations and don't mind the long lead time.
My supplier tells me that he thinks my radiators are oversized, but I like to size my radiators for low water temperatures to increase efficiency, especially with a condensing boiler.

camp10

With all of your helpful input I have fine tuned my calculations using the Runtal correction factors for the commercial radiators and factored in the heat effect for more specific design conditions. I chose to stay with a 150*average water temp and 65* entering air temp as we prefer the rooms a little on the cooler side. For example, in Bedroom 3 with a heat loss of 2782 BTUH, now I will be using a RF-6 x 3.5' long radiator for a total output of 2857 BTUH for the room. The calc used to come up with this: 1981 x .474 x 3.5 / 1.15 = 2857 BTUH output. I will err a little on the larger size to keep the water temperatures low for increased efficiency. Thanks guys.

camp10

Hi guys,
I thought I would post some long overdue pictures of my radiant system. I ended up contacting Alan Forbes for the install and start-up of the boiler, indirect water heater and boiler buddy. He did a fantastic job! I could not have been happier with the whole process. Alan finished the install about a year ago, and over the winter I finished up all the runtal panel installs and pex runs. Alan commisioned the system in late winter, and we have been enjoying the system ever since. Thanks for all the great advice and wisdom shared on this forum! Boon's how to on the runtal wall plumbed radiators was quite helpful! Thanks guys!

camp10

Runtal Radiators

Brewbeer

Nice ! Looks like a lot of nice clean finish work.
What supply and return temps does it typically run? I have a similar system using both the whn055 and bb30.

Boon

Nice job. I like that you went with some vertical orientations. We weren't sure if the vertical orientation would look "right" so our install was all horizontal orientations, which made it more challenging to reach our output needs.

camp10

Brewbeer said:

Nice ! Looks like a lot of nice clean finish work.
What supply and return temps does it typically run? I have a similar system using both the whn055 and bb30.

Thanks, I am very happy with the finished product. I typically see a Delta T around 5-7* during the mornings this time of year. The radiators were sized to run at 150*F at a design day temp of 29*. Most mornings the temps are in the 40's to low 50's, and the supply temps are right around 120*F.

camp10

Boon said:

Nice job. I like that you went with some vertical orientations. We weren't sure if the vertical orientation would look "right" so our install was all horizontal orientations, which made it more challenging to reach our output needs.

Thanks Boon, my wife and I had most of our furniture picked out, which made placing the radiators a simpler process, and in a couple cases the vertical orientated Runtal's became a necessity. We were happy with the finished look of the vertical radiators, they finished up nice and are really pleasant looking on the wall with the nice clean lines.