Need help with selecting the right radiant system

SD2000

I recently bought a house in San Diego, CA. 2600 sqft, 2 stories built in 1988. I would like to install a radiant floor heating system in the entire house. I am planning on using Cali Bamboo Vinyl flooring. I would love some input on the best way to proceed.

Since radiant heating is rare in San Diego, most contractors I spoke with don't have any experience with it. So my plan is to learn and work with my general contractor to install a simple system (I am open for suggestion here)

I have done some research and I have come across the following system, I would love additional recommendation and review/feedbacks for any of them.

• Manufactured board (like ecowarm or warmboard): these solutions seem nice but they seem to be quite pricy $13.25/sqft for warmboard and $9/ecowarm.
  
• floorheat: these guy have a similar concept to ecowarm and warmboard but they use plastic squares instead of lumber and reflective heat barrier at the bottom. I don't see too many review for these guys. Website https://getfloorheat.com/hydronic-floor-heating-system/
  
• Radiantec: A pure DIY solution where I would need to buy lumber board and cut up for installation, given how expensive labor has gotten, not sure if this is worth it. The review for radiantec hasn't been stellar
  
• Is there another other brand or solution I haven't considered?
  

I have a few other questions

• how big of a system should I get for the heat pump, do I need to do a heat loss analysis for my house since it’s a mild climate zone?
  
• Can I get a nice heat pump and use it to power both my radiant floor and the central air system which currently has aging 30 years old furnace? that way I can use both floor and air heating. Is it worth the effort install a dual system or should I rely exclusively on the radiant floor?
  

ScottSecor

We have used Warmboard, Quick Trac and Thermalboard for retrofit jobs. All have produced more than satifactory results. It really depends what's availabile, what your floors are made of, and many other factors.

As far as a heat loss goes, in my opinion it would be in your best interest to perform the calculations. One of the advantages of installing a new hot water/radiant system from scratch is that you put the exact amount of heat emitters (radiant in your case) in each room. With an accurate heat loss calculation you can determine just how many feet of tubing you need to make the house at the desired temperature (typically seventy degrees). I'm guessing, your outdoor design temperature is forty degrees or thereabouts. The goal is to never know the heating system is operating (or not) and each room is exactly the same temperaure, regardless of how "cold" it is outside.

Unfortunatately, I am not familiar with heat pumps.

Hot_water_fan

A radiant floor is a terrible match for this application (house in an arguably perfect climate) I’m sorry to say. The floor temperature will be extremely low and if you think $13/sqft is pricey, just wait until you see the rest of the system priced out. Why not put a small electric mat in the bathrooms and kitchen and call it a day? 

Jon_blaney

Has your furnace been condemned? They are very long lasting.

hot_rod

Consider radiant warming in bath and kitchen areas, where you stand most often

If you want hydronic based heating, panel radiators are nice and quick for a climate like yours

Alan (California Radiant) Forbes

Why is everyone trying to talk him out of what he reasonably wants? While you're further south than I am, I'm sure you will have days that are cold.

Of all the products I've used, the Ecowarm stands out because it's plywood (not particle board) and it uses 1/2" PEX (not smaller tubing that makes for more loops and larger manifolds).

A heat loss calculation is important for many reasons. Slant Fin has a heat loss app.

If you want to include a heat pump, I'd use it for your radiant and a/c, but you still need a boiler for when the heat pump can't generate enough heat.

Hot_water_fan

@Alan (California Radiant) Forbes because he thought ecowarm was pricey and that’s before the rest of the system and he wants AC.

The house is in San Diego. The heat pump will never run out of capacity there. 

hot_rod

Between 2013 and 2019 590,000 heat pumps were sold in Germany outselling boilers. 

157,00 in 2021. Much of that technology is making it to the US. I think the Taco A2WHP is a German manufactured product?  

Don’t fear the aero thermal heat pumps.

A different skill set to work on, but not more complicated than a mod con, really

Zman

When you do radiant heat in a warm climate, you don't want to do the whole floor. If you do, the floor never gets noticeably warm because it does not need to, if it did, it would overheat the space. The trick would be to only warm key places. Electric radiant is excellent for that application.

Voyager

Absolutely you need to do a heat loss calculation. I suspect this will be very eye opening for you. I can’t imagine you will have enough heat loss in San Diego to use a radiant hydronic system. I suspect it will be very hard to design an efficient system with the low water temps you will need. I would consider electric floor heating in the barefoot areas like bathrooms and maybe kitchen and use heat pump for AC and what little heat you will need. However, a good heat loss calculation will make this much more clear.

LDT

I'm just an engineer and homeowner, but this sounds way overcomplicated. Not only is the radiant floor expensive for San Diego, an air-to-water heat pump is also pricey. I have radiant in the Northeast and LOVE it but have had a very hard time finding an affordable air-to-water heat pump to replace my current propane boiler (because I'm considering going all-electric/solar).

If your goal is what they're calling "beneficial electrification" then I'd say keep it simple as recommended above - electric radiant only in the bathrooms and maybe the kitchen. Mini splits for the rest.

If you're really wedded to full-house radiant and OK with fossil fuels then stick with a boiler until the heat pump technology for air-to-water improves (and price point). IMHO!

Rich_49

hot_rod said:

Between 2013 and 2019 590,000 heat pumps were sold in Germany outselling boilers. 

157,00 in 2021. Much of that technology is making it to the US. I think the Taco A2WHP is a German manufactured product?  

Don’t fear the aero thermal heat pumps.

A different skill set to work on, but not more complicated than a mod con, really

Not everyone knows that Taco will even be releasing an ATWHP mid year Bob .

https://www.tacocomfort.com/wp-content/uploads/2022/02/Taco-2022-SystemM-NR.pdf

Look into Sunboard , much more affordable while not being garbage . Look into radiant ceiling also , I prefer it for more well built , tighter buildings . Oddly enough , so do the end users .

Do yourself a favor and put aside any thoughts of utilizing radiantec ( radiantwreck )

TAG

hot_rod said:

Between 2013 and 2019 590,000 heat pumps were sold in Germany outselling boilers. 

157,00 in 2021. Much of that technology is making it to the US. I think the Taco A2WHP is a German manufactured product?  

Don’t fear the aero thermal heat pumps.

A different skill set to work on, but not more complicated than a mod con, really

I'm waiting for one of these and I hope they make them small enough -- I have a well insulated studio in PA and it can be heated with about 4k of electric. With only propane available the heat pump would be perfect for the radiant wen the building gets redone later this year

SD2000

Thank you for everyone input. Just some context, radiant floor is a bit of a luxurious splurge for us since this will be our forever home, so we don't mind spending a bit more get get a comfortable heating system, plus it will be a huge benefit for my kids with dust allergy and the central air isn't helping their allergy during the winter. As for cost, we have the budget for it, however as a cost conscientious consumer, I am trying to find the most cost effective solution to achieve what we want. I understand the rest of the system can be pricy (aka heat pump), and I just want to cut cost wherever I can aka finding a cheaper subfloor such as RHT, HeatFloor, etc.

since this house is a new purchase, I don't have historical heating bill to know the heat loss, plus I will be replacing all the single pane window with double pane window so the old heating bill approach won't be applicable. any recommendation on how I can calculate the heat loss?

Voyager

SD2000 said:

Thank you for everyone input. Just some context, radiant floor is a bit of a luxurious splurge for us since this will be our forever home, so we don't mind spending a bit more get get a comfortable heating system, plus it will be a huge benefit for my kids with dust allergy and the central air isn't helping their allergy during the winter. As for cost, we have the budget for it, however as a cost conscientious consumer, I am trying to find the most cost effective solution to achieve what we want. I understand the rest of the system can be pricy (aka heat pump), and I just want to cut cost wherever I can aka finding a cheaper subfloor such as RHT, HeatFloor, etc.

since this house is a new purchase, I don't have historical heating bill to know the heat loss, plus I will be replacing all the single pane window with double pane window so the old heating bill approach won't be applicable. any recommendation on how I can calculate the heat loss?

The costs aren’t just the initial capital cost, but also the ongoing operation and maintenance costs. I used degreedays.net to run an analysis using Lindbergh Field weather station and most of your days have 0 degree days and the rest are almost all in single digits. This means you almost never need heat at all and when you do it is minuscule. Many pieces of equipment go bad faster when sitting doing nothing for long periods than from operation (cars, airplanes, boilers, pumps) and your system will be idle 80% of the time. Now modern pumps will run periodically to exercise and help avoid these issues, but putting in a system that will be idle the bulk of the time is generally not good. And boilers need to be maintained, even if not used heavily.

Even though the cost of operation is generally much higher, an electric resistance floor heating system is likely a much better deal. Electric is easy to install, it takes up little space, there is no water to ever leak and damage floors and walls and it is maintenance free for all practical purposes. Given the small amount of heat you will need, I think the cost of operation of electric will be miniscule and the savings on maintenance will be significant. And it is hard to get more maintenance free than electric floor heating. I put it under the tile in my basement bathroom and it is very nice indeed.

As for doing a heat loss calculation, I used the following as my main reference. This Zurn document is well written and covers most of the bases. I read it cover to cover before I started designing and installing my workshop system as I was new to hydronics. This covers heat loss well in chapters 9 and 10 and I did my calculations using a spreadsheet. I tried a couple of online calculators, but it was hard to always know what assumptions they were making and often the inputs were not well explained. By starting with the raw formulas in a spreadsheet, I could know exactly what was going on and what assumptions were being made.

https://www.zurn.com/media-library/web_documents/pdfs/zpm02101-pdf.aspx

When it came time to consider system design and installation, I supplemented the Zurn book with videos from Taco and Caleffi. I probably spent 40 hours reading the Zurn book and watching videos before I really even started and then I spend another probably 40+ hours working through the spreadsheet and calculations to ensure they were correct. It took a lot of time, but as a recent retiree I found it interesting.

Just realize that if you install a hydronic system you will likely spend more money on its maintenance than its operation during its life.

TAG

SD2000 -- There are people you can hire to do a heat loss. You send them a house layout -- window specifications, insulation, all of the required information. Not complex - need to find someone. I ended up getting a guy in FL to do another for me as my correct project is odd building and w/ spray foam there is always some back and forth with people fearful the low numbers for equipment will not work. I'm in PA.

Have used both Warmboard subfloor when doing new and the plate system for retrofits ... slabs naturally. All will work. You need that heat load so you can determine how much heat you need per square foot.

My new project was an old stone building w/ wide wood floors (new and old). Used Warmborad for new and the thicker plates under the old parts of the building. Using the thicker plates came close to the Warmboard output. This allowed me to use one temp water in the whole project.

My guess is in your climate the BTU per square foot will be much lower than mine ... maybe very low. There is no point in spending money on a system that will give you 22 BTU's per square foot if you only need 8. There can be situations where a very tight well insulated building can't have radiant tubing everywhere .... even low temp water will overheat the building. Getting that load is very important.

Hot_water_fan

Just some context, radiant floor is a bit of a luxurious splurge for us since this will be our forever home, so we don't mind spending a bit more get get a comfortable heating system

It’s not the cost, it’s more the expectations. A whole house in-floor heating system won’t be a luxurious experience in your climate, as it’ll be like any other floor in San Diego temperature wise. The spot electric radiant can maximize the warm floor feel in kitchens and bathrooms, but the heat loss should come in low enough that any whole house set up won’t be noticeable. 

Alan (California Radiant) Forbes

The design winter temperature in San Diego county is 10° lower than where I am in the Bay Area. Believe me, his floors will get warm.

BennyV

Looking at the weather in San Diego, there hasn't been a single day yet this year where a reasonably well insulated house would actually need additional heat in the first place. Of course having a heating system is important in case there is an unusual cold snap, but any decent heat pump that is installed for it's A/C abilities in the summer will have more than enough heating capacity.

It seems to have been unseasonably warm this winter, as the 99% design temp is 23F, but considering that the 1% design is 105F, a heat pump with enough cooling capacity will have more than enough heating capacity for seasons where it does get cold enough to warrant heat.

I'd definitely put the money into the best heat pumps you can for A/C performance, as you're in a climate where you're probably running A/C half the year, and heat a few days here or there in a cold year.

With windows and insulation, you want to get the envelope as tight as reasonably possible and solar heat gain as low as you can, which will hurt you a little bit in the winter, but help you a LOT in the summer. The vast majority of your space heating needs in January and February will be met by humans and the BTUs generated from electricity use for regular household needs.

SD2000

may I have a recommendation for good heat pump make and model?

BennyV

SD2000 said:

may I have a recommendation for good heat pump make and model?

Mitsubishi, Fujitsu, Daikin are the big ones that have been doing minisplits for a while. If you have ductwork already, Carrier's Greenspeed is the best in the industry, but make sure the dealer has taken the training on that specific line, as it's easy to screw up if they don't know what they're doing.

EDIT: On second though, while Greenspeed IS the best in the industry, since you rarely need heat at all, I wouldn't focus on heating performance, but look at A/C performance, which might open up a lot more options for ducted heat pumps.