Click here to Find a Contractor in your area.
Welcome! Here are the website rules, as well as some tips for using this forum.

If you've found help here, check back in to let us know how everything worked out.
It's a great way to thank those who helped you.
Need to contact us? Visit https://heatinghelp.com/contact-us/.

Panel radiator questions

PulsePulse Posts: 15Member
edited November 7 in Radiant Heating
#1)
I am using panel rads because I do not want baseboard on every inch of my wall. So..
I am planning to run my boiler @ 120 degrees to maximize efficiency, and sizing my rads at their 120 degree BTU output. How should I size my rads? Exactly at the required BTU loss or should I oversize in some fashion? My design temp difference is 7 degrees based on the 99% rule. I also plan to have an outdoor reset, so that should handle any really cold days by increasing boiler temp?

#2)
I will need 13-14 rads, 16" high(to fit under windows) at various lengths(24-72"). I am not a contractor, so finding someone who will even sell panel rads to me is hard and the rads listed online are too expensive. I did find one company that will sell me Beacon Morris @ ~$150-350ea, which is a lot better than online, but still fairly expensive.

I then took a look at buying from alibaba.com, a chinese site. I know, its china, blah blah blah..anyway.. A company on there has rads that look identical to any other major company, but priced at ~$30-$100. They require a minimum order of 50 and by sea shipping for 50 rads is $1000. I know quality is an issue, but I can buy 3x the rads for the same price of the ones in the US that come from europe. They are made out of colled rolled steel. I am still waiting on a response to see how thick said steel is. ..Maybe someone on here wants to go in on a group buy?..haha

What is your recommendation on buying panel rads?

#3)
As stated previously I need 16" high rads. That eliminates companies like Buderus(Bosch) that do not make that height. I have also eliminated Myson because the longest length they make is 48" and in some areas I need longer than that because I am running at low temps. **EDIT**: My mistake, seems myson makes up to 63" in length.

Pensotti(granby) and EcoStyle are expensive. Runtal is also expensive and I do not need any fancy designs. I eliminated all 3.

Beacon Morris seems to be my best bet, anyone have experience with them? ..are they good quality? Does anyone have any other manufacturers they recommend?

Thank you!


Comments

  • IronmanIronman Posts: 5,212Member
    You'll be sorry if buy Chinese rad's. You get what you pay for; that's why European products cost more. They're top quality.

    What boiler do you have? You can't run that low of a SWT on a cast iron boiler.
    Bob Boan


    You can choose to do what you want, but you cannot choose the consequences.
  • PulsePulse Posts: 15Member
    edited November 7
    The Chinese rads were just an idea. I cannot see myself buying 50 rads from china. I can only hope the European companies are not using Chinese steel..haha

    I do not have a condensing boiler yet, still planning everything, but I will be going with Lochinvar, maybe IBC. No issue there.
  • mattmia2mattmia2 Posts: 232Member
    You can use 2 radiators in the applications where you need more than 48". Distributing the heat around the room and the reduced weight and length for installation and later removal for painting and such later are both huge advantages to using 2 smaller rads than one huge one.
  • PulsePulse Posts: 15Member
    I am going to do a home run system. If I spit radiators that means more runs/pipe and it is more cost to use 2x 36" instead of a single 70-72".

    The heat distribution is a positive, but I don't know if that will really be worth it.

    I also do not have anywhere I can by myson off right at this moment.
  • TAGTAG Posts: 137Member
    Having used Buderus panels in a few of my projects -- you may be looking at this incorrectly. How are you going to control them if at design temp you are already at load w/ 120 water?

    How low can you go?

    Mine are all using an old school Buderus cast boilers w/ logmatic ODR and Buderus indirects. One system is over 25 year and using an Eccomatic. They all have the bypass fitting on the panels and less used rooms have danfoss temp controls.

    All NG fired ... nice heat and economical. Mine would have been way too big running at 120.
  • PulsePulse Posts: 15Member
    edited November 7
    @TAG
    This is how I was figuring it out:
    Lets say a bedroom has a heat loss of ~2000 BTUs at my design temp of 7 degrees. I then pick a 16"x48" panel rad that has an output of 2130 BTU @ 120 for that bedroom. If I get a few days that go into the negatives, my outdoor reset will tell my boiler to increase from 120 to whatever is needed to achieve the extra BTUs.

    I have no idea if this is how it works
  • modconwannabemodconwannabe Posts: 47Member
    I bought several from Hudson Reed in the US (they are I think UK based)--they have a warehouse in NY. I've been largely pleased and they have a range of sizes and styles. Prices have gone up since I bought so I don't know how competitive they are. The only issue was they use metric fittings but they include valves with compression fitting and plug and bleeder, but one or two were missing so I had order them which was annoying. Also install instructions are poor-- they don't have an internal baffle and yet are specced to be installed with both valves on the lower ports, which doesn't make sense to me (their customer support insists the hot water will flow to top and cold automatically exits.... At any rate, I've had them installed nearly 5 years, they're good looking, havn't had leak or other issues, they don't hold heat as well as cast iron but the steel is solid and powder-coat paint ahve been fine.
  • ZmanZman Posts: 5,247Member
    To size the radiators, you start with a room by room heat loss, then size the radiators to that number. If you intend to run at lower water temps, the manufacture will have a deration chart or multiplier you can use to upsize the radiators. I prefer Runtal because they are low profile and reasonably priced.

    I am curious what the 7 degree/99% rule is?

    It appears as though your appetite for a nice efficient system is not in line with your budget.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • IronmanIronman Posts: 5,212Member
    You're probably grossly over-sizing for a very slight bit of efficiency. At 120* SWT, the rad's would have to be about twice the size of what 140* SWT would require. 140* SWT would keep the boiler condensing all the time. Use 140* SWT for sizing. That's what we use for designing a new panel rad system.

    Here's Buderus/Pensoti output data for 4" panel rad's:


    Bob Boan


    You can choose to do what you want, but you cannot choose the consequences.
  • mattmia2mattmia2 Posts: 232Member
    You could still use 2 rads per room and run them series or parallel and home run the room instead of every individual radiator.
  • PulsePulse Posts: 15Member
    edited November 7
    @Zman
    I already did a room by room heat loss.

    Let me copy what I said to TAG:
    Lets say a bedroom has a heat loss of ~2000 BTUs at my design temp of 7 degrees. I then pick a 16"x48" panel rad that has an output of 2130 BTU @ 120 for that bedroom. If I get a few days that go into the negatives, my outdoor reset will tell my boiler to increase from 120 to whatever is needed to achieve the extra BTUs.

    So yes, I am sizing for my heat loss load. I just wanted to make sure that is the correct way.

    Here is an article regarding the 99% rule: https://www.energyvanguard.com/blog/53306/We-Are-the-99-Design-Temperatures-Oversized-HVAC-Systems

    I have not seen any reasonably priced Runtal, but again, I am not a contractor. I see nothing wrong with trying to get a decent prices, as I am not looking for designer rads, just the standard.

    -----

    @Ironman

    If I size at 140, sure it will condense, but only at about 90% efficiency. If I drop down to 120 SWT, I reach about ~95%. I based that on efficiency curve graphs, like the one below:

    You would still design at 140 SWT?

    -----

    @mattmia2
    That is certainly an option to keep in mind, just requires a lot of changes on my part. Larger pex pipe, more rads, ect
  • TAGTAG Posts: 137Member
    edited November 7
    I understand how they are sized ... what happens when you get down that low is the panels need to be huge. When you are not needing full output -- the water temp required is lower than possible with some setups.

    I have used the 4" in a few spots ... typically in spots where a tall narrow one is required. I don't really like them as much as the thinner panels. With higher temp water on a cold day .. the thin ones are great.
  • IronmanIronman Posts: 5,212Member
    Pulse said:

    @Zman
    I already did a room by room heat loss.

    Let me copy what I said to TAG:
    Lets say a bedroom has a heat loss of ~2000 BTUs at my design temp of 7 degrees. I then pick a 16"x48" panel rad that has an output of 2130 BTU @ 120 for that bedroom. If I get a few days that go into the negatives, my outdoor reset will tell my boiler to increase from 120 to whatever is needed to achieve the extra BTUs.

    So yes, I am sizing for my heat loss load. I just wanted to make sure that is the correct way.

    Here is an article regarding the 99% rule: https://www.energyvanguard.com/blog/53306/We-Are-the-99-Design-Temperatures-Oversized-HVAC-Systems

    I have not seen any reasonably priced Runtal, but again, I am not a contractor. I see nothing wrong with trying to get a decent prices, as I am not looking for designer rads, just the standard.

    -----

    @Ironman

    If I size at 140, sure it will condense, but only at about 90% efficiency. If I drop down to 120 SWT, I reach about ~95%. I based that on efficiency curve graphs, like the one below:

    You would still design at 140 SWT?

    -----

    @mattmia2
    That is certainly an option to keep in mind, just requires a lot of changes on my part. Larger pex pipe, more rads, ect

    IDK your locale, but almost nowhere on the east side of the country sees sustained temps in that range except ME.

    You're only gonna see about 2-3% difference in efficiency, and then only when those low ambient temps occure.

    Look a those temps again, they are RWT's, not SWT's.

    I would NOT size for 120* SWT when it involves almost doubling the size of the rad's and their cost. There's no reasonable ROI doing that.

    Look at the mean winter temp for your locale and you'll see how little time you actually spend near design temp.

    Bob Boan


    You can choose to do what you want, but you cannot choose the consequences.
  • PulsePulse Posts: 15Member
    edited November 7
    @Ironman

    Please explain what you mean by sustainable temps?

    I understand they are temps on return. If my SWT is 140 and my return is 125, I hit 90% efficiency. If my SWT is 120 and my return is 105, I hit 94% efficiency.

    I would be able to downsize rads about a foot each. So, for a bedroom instead of a 16x48 @ 2130BTU(120), I could go to 16x36" @ 2546BTU(140). The price difference between those two rad lengths is $46(Beacon morris).

    The question is, should I save ~$50 per rad, one time, or get 4% efficiency.

    13 total rads x average $50 savings = $650 total one time savings

    I think that 4% efficiency might be the better bet over 10-15+ years. ..but I have no idea..haha ..I need to find a calculator

    My average winter temp is probably between 20-25 degrees. I was told not to use that for heat loss, so I figured I would not use it now.

    I am not trying to fight with you, just trying to learn and fully understand :)
  • hot_rodhot_rod Posts: 11,857Member
    Also explore reducing the building load as possible, spray foam is a cheap way to do this. Lower the load and heat emitter size and SWT could be reduced. It's the gift tat keeps on giving.

    The 120 SWT number is being tossed around to allow hydronic systems to be used with GEO and low ambient A2WH's.

    Future proofing your system should you ever want or need to go fossil free. 120F is also available from solar thermal in winter months in most areas, even with flat plate collectors. It is certainly an adequate temperature for most inflow radiant. Ceiling and walls can give good output at those low SWT. It's a surface area game :)

    Research the BIN data for your area to determine how much of the season you are actually at design condition. No harm in boosting up to SWT on design or colder days, most boilers have boost function included in the controls.

    Other low SWT ideas here.
    https://www.caleffi.com/sites/default/files/file/idronics_25_na.pdf

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • ZmanZman Posts: 5,247Member
    As you are discovering, there is a balance between efficiency and cost. For what it is worth, I usually use between 130-140 SWT for sizing the rads. With your climate, if you design to 130 SWT, the outdoor reset will set the temp at 110-115 SWT on your typical heating day. This will give you a system with excellent efficiency. Keep in mind that these are just design numbers, I would recommend experimenting with different parameters ,you can likely set the temps even lower.

    I always find the conversation about value to be fascinating. To me the Runtals' are a nice middle of the road product and the boutique brands are extravagant. It would be interesting to see a cost per BTU comparison.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • PulsePulse Posts: 15Member
    edited November 8
    I have been playing with the numbers and as everyone has said planning for 140 SWT in rads is a good idea. :)

    It allows me to not only drop down in rad lengths, but also go from 4-1/8" down to 2-7/8" in thickness.

    I should be running at even lower than 120 SWT for most of the normal winter days.

    My top choices for rads are Beacon Morris or Myson. Only real difference is Myson has connections on the bottom middle while Beacon has them on the bottom side.
  • TAGTAG Posts: 137Member
    keep in mind that you can get an exact match in each space -- how will you control? That's the nice thing about the units with the valve head .. coupled with the bypass fitting. Control with simple piping.

    I have mine daisy chained using the bypass fitting and PEX -- As long as you watch the total loop BTU on the manifold it's easy installation.

    More money -- simple piping

  • PulsePulse Posts: 15Member
    @TAG
    What do you mean an exact match?

    I havent decided completely on control yet. The basement and large kitchen/dining/great room will each have a wall thermostat. In the bedrooms I will probably do TRVs or those valves right on the manifold.

    If you had multiple rads in a single room, you ran them in series off of a single home run?
  • TAGTAG Posts: 137Member
    The first time I used the Buderus Panels was for a very large traditional brick/stone house built in the 40's. I was able to add radiant in much of the main level -- but, the lower and upper floors was best done with panels. Most of the rooms required two panels -- placed under windows. At any given water temp there was no exact match to the heat loss in a given room -- or room to room. In some situations a particular dimension of panel looked the best ... All panels were slightly oversized. I used the thicker 4" panels in a glass porch so I could turn them up and down with faster response. They all work off the boilers outdoor reset curve. The Buderus panels have in/out fitting on the bottom right that will take a chrome bypass ... this allows you to use PEX into the one radiator and directly to the next ... I believe with 1/2 PEX it was about 13k BTU limit on each loop from the manifold. The panels work off a a 7 zone manifold and one pump. The great thing about the Buderus panels is they have the valve/ fitting for the danfoss thermostatic head. With the bypass and the head ... each panel is a independent temp control. You can actually zone one side of a room to be warmer vs another. Turn down one whole room etc.

    There are generic versions of the Buderus panels. The heads are about $50 and the bypass fitting is around $75 ... not the cheapest way to go ... but simple, straightforward piping and self contained.
  • mattmia2mattmia2 Posts: 232Member
    He means that the output of the radiator exactly matches the heat loss of the room.

    Look at the installation instructions for some of the radiators, they give piping examples, there are numerous ways you can pipe them.

    There is a bypass valve like this that fits right on the radiator so you can pipe them in series but get parallel flow as if you had a supply and return off a main to each radiator. You can put them in series without the bypass but they may not heat evenly depending on the flow:
    https://www.supplyhouse.com/Buderus-1016311-Radiator-Straight-Diverter-Valve

    I have a question, the European radiators that have the built in valve for a TRV or flowsetting, can that valve be removed and plugged to allow full slow if you are controlling it from a zone valve and t-stat so that you don't get the restriction from the valve?
  • IronmanIronman Posts: 5,212Member
    mattmia2 said:

    He means that the output of the radiator exactly matches the heat loss of the room.

    Look at the installation instructions for some of the radiators, they give piping examples, there are numerous ways you can pipe them.

    There is a bypass valve like this that fits right on the radiator so you can pipe them in series but get parallel flow as if you had a supply and return off a main to each radiator. You can put them in series without the bypass but they may not heat evenly depending on the flow:
    https://www.supplyhouse.com/Buderus-1016311-Radiator-Straight-Diverter-Valve

    I have a question, the European radiators that have the built in valve for a TRV or flowsetting, can that valve be removed and plugged to allow full slow if you are controlling it from a zone valve and t-stat so that you don't get the restriction from the valve?

    Just leave the plastic cap backed out to where it's not depressing the pin. Turn the brass flow setter ring to fully open.

    Bob Boan


    You can choose to do what you want, but you cannot choose the consequences.
  • TAGTAG Posts: 137Member
    Yes that's the fitting .... there is also an angled. Looks like they have been updated/ changed. I used the angled where I could as it made the connections invisible.

    The angled also required a bit more space behind the panel -- I actually mounted all of mine on vertical strips of 5/4 stock. The mount for the thinner panels put them against the wall. Even the straight pipe fitting would hit the base/shoe moulding.

    With that house the area with the largest heat loss was used for the boiler curve w/ constant circulation in heating season -- those panels did not get the thermo head. As stated above there is a red cap that comes with the unit to protect the valve when the head is not used ... This cap will also close the valve if you want to turn down the panel.

    I also have Runtal towel racks in the bathrooms -- they run off a dedicated loop of the manifold with a thermostat and zone valve. Same water temp.





Sign In or Register to comment.

Welcome

It looks like you're new here. If you want to get involved, click one of these buttons!