Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.
Mod-Con HWHs: When Can They Be Used As Boilers?
D107
Member Posts: 1,906
Several fine contractors have recommended installing a mod-con hwh as a boiler for my 40-50Kbtu NY home. (Versa Flame is one suggestion.) Seems to cut down considerably on installation costs since the unit serves as a boiler, hwh and buffer tank all in one. And because of the buffer tank function, oversizing it a bit--if smaller sizes are not available--seems not so critical since it would not be short cycling. I'm assuming these type of units are every bit as rugged as mod con boilers in terms of handling the duty cycle.
0
Comments
-
I should also verify if its buffer tank function obviates the need for super-close load-sizing.0
-
-
You're saying that in certain situations boiler/indirect would work and hwh wouldn't? Have to do with type of emitters? Are hwh usually used with underfloor radiant heat? In our case two of three heated floors are mostly oversized cast iron; basement has 30ft of baseboard which I'm contemplating converting to cast iron baseboard or radiators. House has been fairly well insulated. About VersaFlame, I was told despite its being discontinued, the components can be put together.1
-
If you need a SWT of 180F at design, a HWH would be a poor choice.
Versa Flame, if available, offers that capability but you'd be storing a lot of water at elevated temperatures just to make DHW via the FPHX.
A HWH can be an economical choice when coupled with a FPHX for CH (Versa Hydro) provided the building can be heated with reduced SWT (160F max in the case of Versa Hydro.............145F max with a traditional HWH).0 -
The expectation is that SWT would be lower than 140 at design. As for hot water, we've been fine (two people) with a 50 gallon HWH that fires at 30Kbtu, set at 140degrees with mixing valve down to 115-120º.0
-
-
If heating supply temp is 150º and return temp is 130 then it's considered condensing, yes? (Heat loss is really likely closer to 30Kbtu but I used 40-50kbtu just for some headroom.) So that sounds good.0
-
Well, it's on the ragged edge.
Here is the efficiency curve for the Lochinvar Knight. Consider it typical.
http://www.lochinvar.com/_linefiles/Knight XL Efficiency Curve-2013.pdf
You really don't get serious with regard to the efficiency until the RWT drops below 100F. That's very difficult to accomplish. However, each time you draw DHW, the makeup water (supply) is well below 100F.0 -
Pioneer with FPHX = Versa Flame . Standby losses are miniscule . Seymour Cates may not be aware but myself and another long ago site visitor designed a very nice system in the case it was ever a good fit in the absence of the Versa Flame .
that idea was in case the system required higher water temps . If higher temps are not required the Phoenix or Light Duty with FPHX would be considered .
Once someone visits the home and performs a heat loss calc we can really discuss this with some substance , until then we're all just guessing . Gonna refrain from commenting further since David has contacted me awhile ago about performing the heat loads / design and possibly having Ezzy T do whatever work is required . Do not wanna muddy the waters or influence open discussion . have at it folks .You didn't get what you didn't pay for and it will never be what you thought it would .
Langans Plumbing & Heating LLC
732-751-1560
Serving most of New Jersey, Eastern Pa .
Consultation, Design & Installation anywhere
Rich McGrath 732-581-38330 -
Yes, I am very impressed with both his knowledge and creativity. As we go forward I am developing a set of general criteria for any jump from my current old atmospheric to mod-con hwh-boiler-buffer tank:
1. Does such a setup have same durability as mod-con boiler and indirect hwh?
2. What is track record in the field for the specific model's performance over time?
3. Are parts readily available at reasonable prices?
4. Are annual maintenance AND repairs relatively simple for local contractors to handle?
5. Will complexity of system--with variable speed circs etc––lead to more repairs?
6. Does the buffer tank aspect reduce the need for an optimum match between firing rates and heat loss, since short-cycling would not occur?
7. Given that heat and hw will be from a single source--as opposed to my current stand-alone gas hwh--would I need to invest in some kind of generator or backup battery system for boiler down time or loss of power?
8. Will unit work well with hard water with chlorides?
ROI is not that high a concern, though I'll certainly make comparisons for overall price tag and economy over time. My current 36 year old boiler and old flue might well last another ten years--but it might not; my 10 yr old hwh I'd otherwise change out in a year or so. I'd rather not do these changeouts in a rush in mid-winter with the nearest installer who happened to have the time.0 -
Good question to ask your installer (if he's selling you the HWH), or the supply house if you're buying it direct.David107 said:
....Are parts readily available ..
If your looking for same day replacement parts.. I can almost guarantee you the answer will be no.
If you're referring to HTP, spares seem to be reasonably priced- $6 for a flame sensor, $226 for a main board for the UFT-80W.David107 said:
.... at reasonable prices?
-1 -
-
@David107
So.........You're asking every question you should be asking the contractor, in an open forum? At some point, you have to trust your contractor. Realize that if you ask a group of people their opinion about anything, you will not get complete agreement. I can't see how this helps you with the vetting process. I understand wanting to be careful. Look at their work. Talk to references.0 -
@Paul48 I understand that opinions vary; but I've found that on this site different opinions are helpful in helping accumulate enough knowledge to make an informed decision. I'll never come near knowing or try to know what Rich and many of you guys know. When I have him down to do the heat loss many of those questions will better be answered. From preliminary conversations I can already say that I have great trust in the design and installation expertise; it's the equipment and future maintenance issues that concern me more.0
-
-
I always ask for photos of a contractor's work; as you say most are proud to show them. Suffice to say that the Wallies that I've met or done business with are such a breath of fresh air compared to the rest of the competition--full of great curiosity, knowledge and passion for their work.0
Categories
- All Categories
- 86.5K THE MAIN WALL
- 3.1K A-C, Heat Pumps & Refrigeration
- 53 Biomass
- 423 Carbon Monoxide Awareness
- 94 Chimneys & Flues
- 2K Domestic Hot Water
- 5.5K Gas Heating
- 101 Geothermal
- 156 Indoor-Air Quality
- 3.5K Oil Heating
- 64 Pipe Deterioration
- 927 Plumbing
- 6.1K Radiant Heating
- 383 Solar
- 15.1K Strictly Steam
- 3.3K Thermostats and Controls
- 54 Water Quality
- 41 Industry Classes
- 48 Job Opportunities
- 17 Recall Announcements