I’ve been doing some custom woodwork on a house boat a guy is renovating. Since it’s summer and quite warm here in Maryland the folks are running their AC. I raised a question about heat this winter (they are planning on living on this thing year round, kids are grown, sold the big house etc.). I suggested radiant heat installed under the plywood subfloor (there is easy access to the under side). I’ve used radiant heat of this type before but we installed a new gas fired boiler to provide the hot water. My question is this, I’ve seen a plumber in this area use a water heater as a source for providing hot water to several small radiators. They had a small circulator pump installed in line which was connected to the T-Stat. Has anyone ever seen this done? If so, do you think it could work with the radiant heat. The boat has about 500 square feet of floor space to heat.
How about that for a goofy post!
Thanks for any ideas!!!!
Good times, riches and son of a _itches,
I’ve seen more than I can recall………..
J Buffett
PLP
Replies
Stop & think about it .... what's a boiler other than a hot water heater? Efficiency issues aside, there's really not much of a difference. There might be a problem with recovery but ... given that a domestic hot water heater is designed to furnish gobs of hot water for clothes washing, showers and the like, it doesn't seem like it should be a problem.
Over time, one aspect of maintenance should be regular flushing of the system to rid it of sediment and such. Figuring out how to provide automatic make-up water might be a sticky wickett. Lots guzinta the design of these types of systems,... more than just source of hot water, some pipe and a heat source - but you know all that.
Dennis in Bellevue WA
[email protected]
this is done quite often, and in the archives you should find an excellent article on this subject, posted by someone in the last six months.
A water heater is way cheaper to buy, but not as efficient to run (so the tradeoffs decide which way to go).
Plumbing for one is straightforward, as long as consideration is given for separation of the pottable water from the heating fluid (often has some antifreeze in it, just in case) by a good head exchanger.
The advantage of a CI boiler is longevity, max efficiency for a big system, and ease of understanding by your heating guy (not all heating professionals agree with using a water heater for this task!).
Norm
I beg to differ with you on a number of points.
1. There are a LOT of differences other than effienency between a water heater and a boiler.
2. Recovery is a HUGE issue. Water heaters have pathetic recovery rates. There is a difference between dump loads and continious use loads.
3. You should never flush a closed loop heating system after the initial purging.
4. A better way than automatic make up water would be to install a low water cut off or LWCO for short.
Thank you.
How was Alaska? Or are you still there? I've been waiting for your return as I'm embarking on a RFH project myself...actually already under-way with PEX and a manifold already installed in a workshop slab.
What is your recommendation for carpet and pad (DW insists) over a sleeper/plate/tube system? I have learned so far that virgin rubber is best for pad...and I'm inclined to think that a berber type carpet will have a lower R-value than plush. This will be on two bedrooms and a 20X24 great room, the rest of the the house will be hardwood or tile.
One alternative that comes to mind is fin-tubes in the capeted areas and RFH under hardwood or tile.
I'm at the point where I'm figuring approximate costs and how much, what parts of, and if any to sub out...and to gain enough knowledge to intelligently discuss these issues with a RFH sub.
What additional calculations will be helpful at this point?
Thanks.
Hey WetHead.
As the expert on such subjects, what is your opinion on the initial question. Would this work ok for a small 500 sq. ft. system?
Also, does what I wrote earlier make sense, or do you think I am spreading bad info?
My house came with a 75 gallon Bradford White water heater. It has an internal exchanger, and I have been told that it's a great choice for a radiant system, but haven't researched far enough to know if this makes sense.
What do you think.
Background: I live in Idaho, 5000ft elevation, cold winters. I'm thinking seriously of using this for suplimental heat in my basement. The forced air keeps the main floor plenty warm, but the basement stays pretty chilly. Eventually I plan to eliminate the forced air entirely, as my basement has a 7' ceiling, and getting rid of the ductwork would be a huge advantage for me. I assume that if I do this, heating 3200 sq. ft. I'd be best served with a high efficency boiler.
Any thoughts, suggestions, web-sites, books, articles I should look at? I've yet to find anyone locally who knows much more then I do about radiant heat. If I pay someone to put in a system, I want one who knows a ton more then I do. You do any work in Idaho??<G>
I'll be quiet now.
BillyG
I'll try to answer your questions in more detail later.
But for now let me say I have no problem with what you are saying. Remember, while I am a professional at this, I am not immune to making errors and ommissions in my advice. Compare my advice with the advice you can get from other INFORMED, EDUCATED, KNOWLEDGABLE, and QUALITY FOCUSSED PROFESSIONALS and then take what makes sense to you. I also believe someone like Mr Thomas is a professional at this even though he does not make his living doing it like I do.
My biggest complaint is when those who don't have a clue spout off their uninformed opinions as fact. Not pointing fingers at anyone. Just a very generalized observation. Billy, you are not doing that.
I suggest that unless someone knows what they are talking about that they should just say what has worked for them under their specific circumstances and not try to pass off their extremely limited knowledge as fact.
Do you see me spouting off about roofing materials? NO! And I know a lot more about roofing materials than many carps. Do you see me spouting off about trusses? NO! And I hang out at a truss plant all the time (friends own it and work there) asking questions.
Does that mean I cannot add value to a discussion on roofing materials or on trusses? No. But neither do I have any business passing off my observations as factual advice.
OK, rant over. Back to work everyone.
Thanks. I'll look forward to hearing your thoughts later.
Just as a personal thing I've decided to eventually go with radiant heat. It'll make my basement much nicer when I finish it. Air conditioning isn't a huge deal here, though I may put in some smaller ductwork to leave that possibility open (not sure yet if this is feasible). Money's not there yet, so I haven't gotten too involved.
Biggest sticking point has been overall layout of a utility room to house everything. I have lots of Southern exposure so intend to build it so I can add some hot water solar panels later. Must be a local expert on this stuff. Need to find him.
Billy,
Look at the Budarus direct vent boiler it fits in a small space, no chimney, low cost. Like WHW says, I am not a pro however its working out great for me.
Jason
PS you can stack the water tank under it.If it wasn't for bad luck I wouldn't have Any!
Thanks, I'll take a look at them.
This may work ok for the initial poster also.
http://www.spnwsupply.com/L3-products/boilers1/buderusGas.html
This site states you can put one in a closet with 2" of clearance. My spaces aren't real tight, but on a boat they sure would be.
Edit: Here's their homepage. http://www.buderus.net/
Wethead, what's your opinion on the best boiler overall? Best for the money, ect.? I'm clueless.
As usual.
Edited 8/5/2003 5:57:07 PM ET by BILLYG83440
Edited 8/5/2003 5:59:54 PM ET by BILLYG83440
Just got in from work and was quite supprised at the response. Thanks to all for the input. I'm going to check out a few of the noted web sites.
Again...........Thanks!
PLP
Good times, riches.... and son of a _itches,
I've seen more than I can recall!
There are a lot of sites on the web that discuss this. I used to have many of them bookmarked, but my browser crashed and I lost it.
Some are totally for this, some are totally against it. I know Bradford White builds many of their water heaters with a built in heat exchanger that can be used for this purpose. Mine at home is one such, I'd assume other makers of water heaters build theirs the same way. This makes it very simple to do. Usually as a closed system with a circulator pump moving the water through the loop.
From what I remember, this works especially well for smaller systems. Boilers are more efficent, but especially when delivering larger volumes. Water heaters do better with the smaller systems. The articles I read discussed how in smaller systems you lose a great deal of the increased efficency of the boiler.
Overall, it seemed like the best way to go to me. At least for small systems.
WHW may still be in Alaska. I definitely am.
I use a 42,000 BTU/hour HWH in my own house. The houseboat probably doesn't see -40F temperatures but probably isn't nearly as tight (above the water line) nor as well insulated as my house.
If it is pretty well insulated, only subject to 30F temperatures and 500 square feet, then the heat load would, roughly, 6,000 BTU/hour. So low that the increased time to recovery from multiple showers would be hard to notice. If it is poorly insulated and needs to stay warm at 30F then it needs about 15,000 to 20,000 BTU/hour. Which any HWH would put out, but the recovery time would take a hit. Yet, come shower time, it would have 40 gallons of hot water in it, only the time till the next long (or multiple) shower is hurt.
An advantage of a HWH instead of a boiler is the saved cost (HWH only instead of HWH and boiler) and the saved space. At $100-150/square foot to build a house, you save $2,000 to $3,000 if you don't have to site a boiler with wall clearance and maintenance access. I've never known anyone living on a boat who had too much space!
Let me be clear. I am not against using a WH for this application. I was only trying to correct bad information.