HTP · Mod Con Commercial Gas Boiler
HTP Mod Con 500
The HTP Mod Con 500 is the 500 MBH class model of HTP's discontinued commercial condensing boiler line: 100 to 500 Btu/hr input, 470 MBH heating capacity and 94% printed thermal efficiency in a 505 lb floor-standing cabinet.
Key figures
- Max input
- 500 MBH
- Max CSA output
- —
- AFUE
- —
- Min input
- 100 MBH
Input is gas energy consumed; output is heat delivered. Never size from input alone.
HTP Mod Con 500 in practice
The Mod Con 500 is documented on HTP's retired Mod Con page as part of 'a highly efficient modulating condensing boiler that operates with up to a 98% thermal efficiency rating', built with a 316L stainless steel water-tube heat exchanger, a high-grade Inconel burner and up to a 5 to 1 turndown. The printed model table lists the Mod Con 500 at 100–500 Btu/hr and 94% thermal efficiency.
The lp-445-r4 installation manual (boilers manufactured after August 13, 2013) supplies the rating rows used here: 470 MBH heating capacity, a 505 lb shipping weight, 4.2 gal of boiler water content, a 33 GPM minimum flow rate at a 30 °F ΔT, 2" NPT supply/return, a 1-1/2" NPTF gas inlet, the 4" (200 ft) max combined, 16 ft minimum vent allowance and 120 V / 60 Hz / 6.3 A power. The boiler vents Category IV in PVC, CPVC, polypropylene or stainless steel up to 200 equivalent feet combined, and the 926 SIT control supports outdoor reset with indirect priority, 0-10 VDC BMS input and cascade wiring for up to eight boilers.
The Mod Con is retired: 'Mod Con Commercial Gas Boiler' is listed on HTP's official discontinued-products index, and LP-466 prints 'Models available for Natural or LP Gas' with an ASME 75 PSI relief valve and SCAQMD low-NOx certification. Boilers.ca records the model with productStatus 'discontinued' and canadianStatus 'unknown'; owners should have an installed unit serviced by a licensed contractor against lp-445-r4.
Best suited to
- Existing Mod Con 500 installations needing identification and service planning
- Plants that already use the 926 control and cascade wiring for up to eight boilers
- Retrofit decisions comparing a retired Mod Con plant against current commercial boilers
Applicability and support
- Model number
- Mod Con 500
- Canadian availability
- unknown
- Production status
- discontinued
- ROMA supplies
- Confirmed at consultation
- ROMA services
- Confirmed at consultation
- Warranty
- Series terms
Where ROMA provides on-site service
On-site service is currently offered in Greater Vancouver, BC, including Vancouver, Burnaby, Richmond, Surrey, Coquitlam, North Vancouver, West Vancouver, New Westminster, Port Coquitlam, Port Moody, Delta, Langley, Maple Ridge, Abbotsford, Chilliwack, White Rock, Pitt Meadows, Tsawwassen, Anmore, Lions Bay, Belcarra, Bowen Island, Mission. Everything else on this site is reference information you can use anywhere in Canada.
Specifications
Published specifications
Values as published by HTP. Units are shown with every value; notes flag conflicting sources or missing figures.
| Specification | Value | Note |
|---|---|---|
| Input | ||
| Input rate, minimum | 100 MBH | 100,000 Btu/hr, as printed on the official page table and lp-445-r4 Table 2. |
| Input rate, maximum | 500 MBH | 500,000 Btu/hr, as printed on the official page table and lp-445-r4 Table 2. |
| Output | ||
| Heating capacity | 470 MBH | Heating capacity as printed in lp-445-r4 Table 2. |
| Efficiency | ||
| Thermal efficiency | 94 % | As printed per model on the official page table; the page also claims 'up to a 98% thermal efficiency rating'. |
| Venting and air | ||
| Vent size and maximum combined run | 4" (200 ft) max combined, 16 ft minimum | Category IV sealed-combustion direct vent; 16 ft minimum combined run as printed. |
| Approved vent materials | PVC, CPVC, polypropylene or stainless steel | Category IV, sealed-combustion direct vent / power vent; LP-466 prints up to 200 equivalent feet combined intake and exhaust. |
| Physical and connections | ||
| Shipping weight | 505 lb | As printed in lp-445-r4 Table 2. |
| Boiler water content | 4.2 gal | As printed in lp-445-r4 Table 2. |
| Supply / return connection | 2" NPT | As printed in lp-445-r4 Table 2. |
| Gas inlet | 1-1/2" NPTF | As printed in lp-445-r4 Table 2. |
| Dimensions (W x H x D) | 20.5" W x 36" H x 46" D | As printed in lp-445-r4 Table 2. |
| Heat exchanger | 316L stainless steel water tube, 160 PSI ASME stamped, National Board listed, gasketless | LP-466 prints all-stainless construction with a gasketless design, front service access and an ASME 75 PSI relief valve. |
| Water pressure | Heat exchanger MAWP 160 psi; ASME 75 psi relief valve | As printed in LP-466 and the lp-445-r4 technical table. |
| Electrical | ||
| Power supply | 120 V / 60 Hz, 6.3 A | As printed in lp-445-r4 Table 2; ambient temperature range 33–104 °F. |
| Operating limits and other | ||
| Minimum flow rate at 30 °F ΔT | 33 GPM | As printed in lp-445-r4 Table 2. |
| Turndown | Up to 5:1 | Page copy and LP-466 print 'a modulating burner with up to a 5 to 1 turndown ratio'. |
| Control | 926 SIT digital control with LCD and LED indicators | LP-466/lp-445-r4 print LED indicators for system, boiler and DHW pumps, system fault, operation, freeze protection, flame on and fault indication; outdoor reset with indirect priority; 0-10 VDC BMS input; cascade up to 8 boilers. |
| Safety devices | Flame rectifier probe, water temperature high limit switch (190 °F), freeze protection, condensate trap with overflow switch, included low-water cut-off, blocked vent pressure switch | As printed in the lp-445-r4 technical table; UL 353 low-water cut-off interface is an optional kit. |
| Warranty | 10-year limited warranty, no registration required | Page copy and LP-466 print a 10-year limited warranty. |
Manuals
Alerts documented for this model
None documented yet.
Frequently asked questions
What is the input range of the Mod Con 500?
The official page table and lp-445-r4 Table 2 print 100 to 500 Btu/hr with 470 MBH heating capacity.
What efficiency does the Mod Con 500 print?
The official page table prints 94% thermal efficiency for the Mod Con 500; the page's 'up to 98%' claim reflects the line's best printed model.
Is the Mod Con still sold?
No — HTP's discontinued-products index lists 'Mod Con Commercial Gas Boiler'; the product page and manuals remain for support.
Questions about the HTP Mod Con 500?
Describe what the boiler is doing and get a straight answer about the next step.
On-site service in Greater Vancouver, BC. ROMA lists “Open 7 days” on its site; call to confirm same-day availability.
Sources and verification
- HTP — The Mod Con Commercial Gas Boiler (printed model table) · accessed September 9, 2026
- HTP — Mod Con Commercial Gas Boiler Documents · accessed September 9, 2026
- Mod Con Installation Manual (boilers manufactured after August 13, 2013), lp-445-r4 · accessed September 9, 2026
- Mod Con Submittal, lp-466 (7.30.20) · accessed September 9, 2026
- HTP — Discontinued Products index · accessed September 9, 2026
Facts checked September 9, 2026. Last updated September 9, 2026. Technical reviewer: not yet assigned.