FAQ
TL;DR: Replacing a 17.5 kW wood boiler? With a buffer, DS averages ~60% while gasification ~90%, saving ~3 m³/year; “pay back around a decade.” [Elektroda, Xantix, post #17090691]
Why it matters: This FAQ helps Polish homeowners pick a PN-EN 303-5:2012 Class 5–compliant wood boiler that fits budget, fuel, and comfort goals.
Quick-Facts
- Production of non–Class 5 boilers banned from Oct 1; stock sales allowed until July 1, 2018. [Elektroda, puchal.bass, post #17083674]
- As of early 2018, only two batch-loading (manual) boilers met Class 5. [Elektroda, Sstalone, post #17083747]
- DS + buffer ~60% vs gasification + buffer ~90% efficiency; gasification can cost up to 2× more yet save ~540 PLN/yr on 15,000 kWh. [Elektroda, Xantix, post #17090691]
- Class 5 wood boilers bought after July 1, 2018 should connect to a correctly sized buffer; circuits draw from the buffer only. [Elektroda, Baqo, post #18314024]
- MPM DS is a well-regarded bottom‑combustion, batch‑loading wood boiler option. [Elektroda, Xantix, post #17084863]
Quick Facts
- Production of non–Class 5 boilers banned from Oct 1; stock sales allowed until July 1, 2018. [Elektroda, puchal.bass, post #17083674]
- As of early 2018, only two batch-loading (manual) boilers met Class 5. [Elektroda, Sstalone, post #17083747]
- DS + buffer ~60% vs gasification + buffer ~90% efficiency; gasification can cost up to 2× more yet save ~540 PLN/yr on 15,000 kWh. [Elektroda, Xantix, post #17090691]
- Class 5 wood boilers bought after July 1, 2018 should connect to a correctly sized buffer; circuits draw from the buffer only. [Elektroda, Baqo, post #18314024]
- MPM DS is a well-regarded bottom‑combustion, batch‑loading wood boiler option. [Elektroda, Xantix, post #17084863]
What does PN‑EN 303‑5:2012 Class 5 mean for my wood boiler?
It is the emissions class you must meet to comply. From October 1, non‑Class 5 boilers could no longer be produced. Stock could be sold until July 1, 2018. After that, only Class 5 units remained on sale. [Elektroda, puchal.bass, post #17083674]
Can I still buy a non‑Class 5 boiler before July 1, 2018?
Historically, yes. The rule allowed selling existing stock until July 1, 2018. After that, only Class 5 boilers were permitted. Plan based on current local enforcement if buying used. [Elektroda, puchal.bass, post #17083674]
Which is better for burning wood: a DS or a gasification boiler?
Gasification delivers higher efficiency with a buffer, about 90% vs ~60% for DS. DS costs less and tolerates fuel better. Gasifiers need properly seasoned wood; wet wood can quickly damage them. “Pay back around a decade” reflects typical savings. [Elektroda, Xantix, post #17090691]
Will a gasification boiler handle coal if I sometimes burn it?
No. If coal is in the fuel mix, choose a good bottom‑combustion DS boiler instead. Gasification units target wood and control its combustion pathway, not coal. [Elektroda, gaz4, post #17090646]
Is a heat buffer legally required for Class 5 wood boilers?
Yes according to guidance shared: Class 5 wood boilers purchased after July 1, 2018 should work with an appropriately sized buffer. Connect heating circuits only to the buffer. [Elektroda, Baqo, post #18314024]
Should I add a buffer to a DS wood boiler anyway?
Yes. A buffer improves comfort, reduces cycling, and helps achieve steady, clean burns. As one expert put it, “And it’s best to use a heat buffer for it.” [Elektroda, andrzej lukaszewicz, #17088038]
Are gasification boilers worth the extra cost?
Often, they pay back over time. Example: 60% DS vs 90% gasifier with buffer saves ~3 m³ of wood yearly, about 540 PLN. “It will therefore pay back around a decade.” Factor complexity and wood quality demands before deciding. [Elektroda, Xantix, post #17090691]
What size and type should replace my 17.5 kW unit?
Size from your building’s heat demand, insulation, and emitters. Share area, insulation level, occupancy, boiler room setup, and wood prices. Radiators and floor heating behave differently. Provide those details before selecting DS or gasification. [Elektroda, andrzej lukaszewicz, #17094073]
Any recommended bottom‑combustion wood boilers?
Yes. MPM DS is a strong, bottom‑combustion, batch‑loading pick for wood. It balances simplicity, good burn control, and compatibility with a buffer tank. [Elektroda, Xantix, post #17084863]
What about the EKO‑WERY Michał boiler?
See the independent model overview for EKO‑WERY Michał. It covers design, combustion setup, and user‑focused pros and cons to review before purchase. [Elektroda, Xantix, post #17101835]
Can I trust every “Class 5” label in brochures?
Verify the specification, not the flyer. One cited case advertised Class 5, but the spec showed Class 3. “Marketing gibberish.” Always check certified documentation. [Elektroda, Xantix, post #17100982]
Can a converted upper/lower boiler work like a true bottom‑burner?
Yes, if done correctly. Ensure a tight upper partition, a quality ceramic burner, and proper secondary air. “After these modifications it practically does not differ from MPM DS.” [Elektroda, Sstalone, post #17098342]
What are the risks of throttling a gasification boiler in a high‑demand house?
Large heat demand needs a big buffer. Oversizing may be impractical. DS can run throttled with a small buffer; gasifier throttling is risky. “Throttling the holzgas boiler can be a very risky move.” [Elektroda, Xantix, post #17097264]
How do I choose between DS and gasification, step‑by‑step?
- Decide your fuel: wood‑only or wood + coal.
- For wood‑only, consider gasification for higher comfort and control.
- If coal appears, select a good DS boiler instead. [Elektroda, gaz4, post #17090646]
How often can I fire if I use a large buffer?
With a sufficiently large buffer, expect a burn every 2–3 days in shoulder seasons. This reduces daily tending and improves comfort. [Elektroda, gaz4, post #17098572]
Which other brands or designs are worth a look?
Review Orlan and Holz Master gasifiers, plus Sigma. For DS with large chambers, see Vespa Standard. Compare cleaning access, controls, and buffer integration. [Elektroda, gaz4, post #17091825]
