Buderus logano g215 reset button not working

Buderus logano g215 reset button not working. 2. HVAC Supervisor. Contractor's Assistant: I'm sorry to hear that your Buderus furnace is giving you trouble. Buderus G215 Boilers are designed in Europe, where fuel costs are significantly higher and environmental regulations are more stringent. >Note: This item comes with a G215-3 Riello F5 Burner Kit (7738004864). 50 GPH, with an efficiency of 86. Generally, such faults can be reset by pressing the reset button on the burner. V Any work on components that carry oil may only be car-ried out by a certified heating contractor. You should inspect the trap/filter system for dirt clogging and clean it in such a case. 6 720 615 225-04. This needs a professional oil burner mechanic and many plumbers are not equipped to handle oil burner Logano G215 WS - We reserve the right to make any changes due to technical modifications. Yesterday the 10Amp/250Volt fuse on the BLog r2107 Control did its job, is dead and I read more We reserve the right to make any changes due to technical modifications. Nov 13, 2023 · Sometimes it’s become an ignorance factor. Mar 13, 2013 · I have a buderus oil logano g215-4 with a Logamatic 2107. Yesterday the 10Amp/250Volt fuse on the BLog r2107 Control did its job, is dead and I read more Oct 19, 2021 · My Buderus Logano G115/4 burner will not ignite. But the start/stop is not normal. Fred Sherrington 200 White Birch Road Hudson NY 12534 Oct 4, 2014 · Easiest way to see if the reset button works is to upload a sketch and see if the sketch starts over when you press reset. Subject to technical changes! The Buderus Logano GE515 oil- and gas-fired boiler is designed for central heating and delivers efficient and reliable heat for your home. G215/7, which is a 7-section boiler that can be fired at a capacity of 294MBH, 2. We advise holding it for at least 30 seconds. Logano G215 WS will generally be described as the boiler. Oil- and gas-fired boilers (68 pages I had a Buderus G215-6 installed. 6 Installation of Insulated Flexible Oil Vent Apply a ¼" wide bead of high temperature silicone all around the boiler vent connection 1" from the end. The full 3" thick thermal insulation helps to maintain a higher water temperature even after the boiler has gone into standby mode. If the information in this manual is not followed exactly, a fire or explosion may result causing property damage, personal injury or loss of life. Oil and gas-fired boilers (72 pages) Boiler Buderus G315 Assembly, Maintenance And Operating Instruction. "Calculated flue gas temperatures used for cross-sectional 5 days ago · If the reset this PC option is not working, or you are wondering how to force reset Windows 10, you might need to insert an installation media to perform a clean install. The unique way heat flows through the G215 boilers allows the water to be heated three separate times. There are 5 circulators. m. Gas & Oil Boilers and Furnaces Manuals BUDERUS - Logano G215 WS (Mode d'emploi en Anglais) Manuel utilisateur BUDERUS Logano G215 WS - Cette notice d'utilisation originale (ou mode d'emploi ou manuel utilisateur) contient toutes les instructions nécessaires à l'utilisation de l'appareil. (80 pages) Boiler Buderus Logano G215 US Installation And Maintenance Instructions Manual. Nov 15, 2018 · I have a Buderus Logano G215 Boiler with a Riello burner which uses oil and a Buderus Logalux LT DHW Water tank which is heated by the G215. If you hit the reset 6 times you have a potentially very hazardous condition once the burner does ignite. 1 Explanation of symbols. Also, this last solution is important if you can’t reset the PC without a recovery key. Manuals and User Guides for Buderus Logano G215 US. It is important to correctly configure Buderus Logano G215, it will save resources needed to use it. When the end of a paperclip is stuck into the tiny "Reset" hole next to the power plug, the Power LED which is right next to the hole will turn from green to amber and then begin to flash. We reserve the right to make any changes due to technical modifications! Set breaching pressure to -. 62 Removing the blocking plate. Minimum chimney height: 15 ́. an indirect fired hot water tank for single and multiple<br />. We're considering the G215/3 Buderus (. La notice décrit les différentes fonctions ainsi que les principales causes de dysfontionnement. Any help in this regard would be much appreciated. In case of problems, you will also find recommended companies that can properly fix Buderus Logano G215. Circuits may have been broken by cable damage, and the console buttons suddenly ceased working. <br><Br> This thermostream boiler is ideal for new installations or The Buderus G115WS boiler is based on the highly successful G115. buderus. 41,390 satisfied customers. Thank you for reaching out on TP-Link community. Warnings are indicated by a warning triangle and a grey background. No baffles were used with the Riello Burner. 3 Installing system components Seal boiler drain to connection EL. either the lense is dirty or the sensor is failing or the flame is not bright enough for the sensor to "SEE" there is a flame and shuts off by the safety circuit. 3. Le presenti istruzioni d'uso contengono importanti informazioni per un utilizzo e una manutenzione sicuri e appropriati della caldaia sostitutiva Logano. Its compact design allows for flexible installation, while the advanced control system ensures precise temperature regulation and energy efficiency. The installation and maintenance manual is provided for technicians who have been trained and have experience in working with heating systems and oil and gas fired installations. Product Note About these instructions. Recently the boiler has randomly been not firing and the control display reads “Heating Err”. Flexible Cast Iron; The heat exchanger of the Buderus G215 boiler is made of patented flexible cast iron, allowing the boiler to resist even the most punishing thermal shock. These settings do not super Buderus Logano G215 — Heating Help: The Wall I work for a small plumbing and heating company and we have been having a problem with a Buderus Logano G215 with a Riello gun on it. Several treadmill console buttons are fixed annually because children have been broken or over-pressed by children. and 4:40 Description of Buderus Logano G215 US. My tax guy wants to know (and so do I!) if it qualifies for the Energy Star tax credit in the US. I was going to use waste oil but my source dried up. First there is a click and then within 10-15 seconds Sep 29, 2014 · RBD. Open the main gas supply and press reset. Process of elimination. NOTE: For reference only. It’s serviced annually by a local oil Jan 4, 2022 · 4/18/11 I have a Buderus oil Logano G215 US boiler, a Buderus r2107 Logmatic Control , and a Riello 40 F5 burner. Buderus G215-3 - 117,000 BTU Output Logano G215-3 Cast Iron Oil Boiler w/ Burner- Note: Product Title reflects this boiler's IBR Net Output Rating. I've never had one read more Table of Contents. Mar 4, 2020 · Re: Reset Button not working Perhaps there is a misunderstanding. Step 3: Separate the front (from the back) Step 4: Inspect the front part. Buderus G215/7 - 294K BTU - 86. Product Note Buderus 7738000112 G215 Series 196 Input MBtu Logano Thermostream Oil-Fired Boiler - Knockdown (Burner Sold Separately) Buderus boiler sections are assembled with beveled, surface profiled push nipples for long, trouble-free watertight operation. Mar 4, 2018 · I havea Buderus Logano G334 boiler (installed in 2012) that will not ignite. I have 3 zones, one for the domestic hot water, one for the 1st floor and one for the 2nd floor. use in space heating and domestic hot water heating using<br />. Feb 14, 2016 · I have a Buderus Logano G115 which is controlled by a HS2105. Per un perfetto funzionamento l’impianto necessita del giusto combustibile. Insufficient ventilation may cause dangerous flue gas leaks. I have a Buderus Logano G215. Established in 1731, Buderus uses state-of-the-art techniques in the design and manufacturing of its boilers. G215/6, which is a 6-section boiler that can be fired at a capacity of 256MBH, 2. net. Buderus Hydronic Systems, Inc. It describes the boiler components and control systems. the Energy Kinetics System read more. I've never had one read more Aug 8, 2016 · Obstructed airflow: Sometimes the reset button gets tripped because the furnace isn't receiving enough airflow. Each of these symptoms can indicate a larger issue with your ground fault interrupter. 7 Checking the high Limit cut-out (STB) The high limit cut-out interrupts the power supply if the maximum permissible flow temperature is exceeded. 1. Step 6: Re-assemble the unit. 03 In. Repeat this until the blades start to rotate freely. Ratings based on a heating value of 140,000 Btu/gal of No. 1RS Fig. V Do not use or store flammable (paper, thinners, paints, etc. #10 · Oct 3, 2014. To enable a boiler reset and re-starting, the fault must be Fig. Then, after a few minutes, it will start. EPA certified residential refr 853 satisfied customers. the boiler is vented through the chimminey which is clay lined and is the only thing the chimmney is used for. <br />. Step 5: Clean the dirt off. Constructed without a heat I have a Buderus Logano G215 Boiler with a Riello burner which uses oil and a Buderus Logalux LT DHW Water tank which is heated by the G215. Buderus G215-4-NO-BURNER - 149,000 BTU Output Logano G215-4 Cast Iron Oil Boiler (No Burner)- Note: This item does not come with a burner<br><br> The Logano G215 is a three-pass boiler that allows water to be heated three separate times. 50 Wentworth Avenue Londonderry, New Hampshire 03053, USA. This user manual provides instructions for safely operating an oil or gas-fired boiler. 10 GPH, with an efficiency of 86. 1 With respect to this manual; 1. In the following, the oil-/gas-fired special boiler. Secure the control panel with self-tapping screws. 50 Wentworth AvenueLondonderry, New Hampshire 03053, USAPhone: (001) 603 552 1100Fax: (001) 603 421 2719Internet: www. See the installation diagram for installation of the heating system components. 2. No baffles are furnished with the G215/6 and G215/7. ) near the boiler. Hi there. "ALWAYS KEEP THE MANUAL FUEL SUPPLY VALVE SHUT OFF IF THE BURNER IS SHUT DOWN FOR AN EXTENDED PERIOD OF TIME. 1. Buderus G215/7 Logano series model is Energy Star listed, floor-standing, 7-section, residential oil-fired boiler with 87% AFUE and 256,000 BTU (Net) rating. I have a buderus oil logano g215-4 with a Logamatic 2107. This switches the boiler and all its components OFF (for example the burner). 2 Switching off the heating system. 1 Mar 5, 2023 · Insert a 1/4 inch Allen wrench into the hex hole under the disposal and rotate it to and fro until the blades are free. Honeywell thermostat buttons not working – what to do. AFUE - Hot Water Oil Boiler - Chimney Vent. 2 Installation of boiler drain (included in B-Kit) 5. Danger! If installation, adjustment, modification, operation or maintenance of the heating. Yesterday it decided to go into summer mode, measuring outside air temp. New Thermostream technology allows for unrestricted return water temperature and eliminates thermal shock. With this type of Riell Nov 15, 2021 · Keep the pilot gas supply line open, and turn off the main supply. These user's Instructions contain important information for the safe and proper operation of GB142-24/30/45/60 condensing gas boilers. Installation and maintenance instructions Logano G215 US oil/gas-fired boilers † Issue 2021/07 Remove the Logamatic control panel cover. If there is no hex hole beneath your disposer, insert a long broom handle through the sink hole and rotate the blades. Tonight we can read more Jun 27, 2017 · First, try to use the System File Checker tool to repair missing or corrupted system files. If both the cruise and trip aren't working, time to start checking for continuity. " Step 6 (Unclog the trap/filter system) If the non-responsive button is flashing, that’s a sign that the trap/filter system is dirt clogged. Internet: www. Risk of poisoning. 0% AFUE. removed and the system must have fallen back below the limit. Once you've created the new profile, click on the new profile's icon Jan 16, 2015 · The boiler is certified as a hot water heating boiler for<br />. The G115WS has been redesigned and reengineered to extract and deliver more heat from fuel, and now has higher outputs at less cost per BTU. Close the main fuel shut-off valve. These installation and maintenance instructions are designed for specialists, who, – through their Page 26 Boiler Installation 7. Step 2: Remove the battery compartment. The max number of times you should hit the reset is twice. Is the puff of smoke coming from the furnace itself? Yes, where the burner enters Three-Pass System. I reset it to winter mode, but it won't fire in automatic mode and it is still measuring the outside air temp 20 -30 degrees warmer than it actually is. Disclaimer: Information in questions answers, and Show Less. I'm sure this is a hot topic these days when oil is $3. Connect the fuel pipe to the boiler; it must be free of stress. Jan 7, 2020 · I purchased a house with a Buderus Logano G215 paired with a Riello 40 F5 burner that provides DHW and 3 zones of heating via circulators feeding hydro air units. If it doesn't help, try to create a new local account (administrator) following the steps in this guide. 90 a gallonI just saw on Buderus' website that they have a Reillo gas burner for the G215. Push the reset button. 8 Reset button Item 1: Reset button We reserve the right to make any changes due to technical modifications View and download the Manual of Buderus Logano G215 Boiler (page 1 of 12) (Dutch). Buderus G215 User Manual - Free download as PDF File (. Table Of Contents. Logano G115: Models from 74,000-120,000 BTU/Hr Heating Capacity. Normally, it is a two-step process after flipping on the power switch. I bought this house which had been vacant for about 12 months and had about 1/8 th heating oil in each connected Roth 250USG tanks in the mechnical roo The oil and gas fired boiler Logano G215 is generally referred to below as a boiler. Follow the harness under the dash and start checking for continuity at the switches. You likely had air in the system from the leaking gaskets. The lights on the HS2105 were blinking between the top light with the Auto button read more. Please make sure the camera has been reset correctly as per the User Guide. For furnaces with sealed pilot compartments, press the red button right under the pilot or seal to start and turn on the power. Read carefully before carrying out installation and maintenance. 2 Fuel Oil, breaching draft of -. We had it serviced in Feb '19 by the HVAC company that replaced our Hydro Air handlers and Outdoor condensers and they screwed it up and it kept locking out and puffing back for months. You may have a defective GFCI, insufficient current, or have a GFCI that's wired incorrectly. Above settings were established with baffles in place on the G215/3, G215/4 & G215/5 boilers. Yesterday the 10Amp/250Volt fuse on the BLog r2107 Control did its job, is dead and I read more Open the catalog to page 2. Logano G215 WS - We reserve the right to make any changes due to technical modifications. Reset: Press and hold the reset button for at least 5 seconds until the LED blinks red to reset your camera. It explains how to turn the boiler system on and off, conduct emergency shutdowns, and test the Buderus G215/4 Logano series model is Energy Star listed, floor-standing, 4-section, residential oil-fired boiler with 87% AFUE and 149,000 BTU (Net) rating. Yesterday the 10Amp/250Volt fuse on the BLog r2107 Control did its job, is dead and I read more Aug 13, 2011 · 4/18/11 I have a Buderus oil Logano G215 US boiler, a Buderus r2107 Logmatic Control , and a Riello 40 F5 burner. The G215 boiler is ideal for both new construction and renovations of aged housing due to its adaptive heat exchanger and optimal connection placement. Do not store or use gasoline or any other flammable liquids or vapors in the vicinity of this system or any other heating system. >Note: This item comes with a Riello F10 Burner Kit (7738004868). Dec 24, 2023 · Our furnace is a buderus g215, stopped working last night, got it reset (I think) and nw starts, but with a puff of smoke - recommendatins?. Dec 12, 2013 · I assume you are hitting the reset button to get the burner to retry ignition. It heats the house alright. V Maintain a clearance of at least 16 inches from the boiler. Signal words are used to indicate the level of risk if counter measures are not taken. Reset button pops out whenever you turn on an appliance plugged into the outlet. We're considering the G215/3 Buderus (134K BTU output) vs. at 90 degrees when it was in the forties. Fax: (001) 603 421 2719. 02 to -. The last time I noticed this the tech said it might be an aqua stat problem. When you hit the reset it fires right up and runs fine. kpc_16. More detailed information can be found in the controls' documentation. C. Perform only those operations to your heating system<br />. family homes. Yesterday the 10Amp/250Volt fuse on the BLog r2107 Control did its job, is dead and I read more Note: This item does NOT comes with a Riello F10 Burner Kit (7738004868). This particular Buderus boiler meets our clients needs because it is energy-efficient, performs remarkably, and has a long lifespan. Telefon: (001) 603 552 1100. 7% AFUE. in particular must only be carried out by suitably qualified personnel. May 22, 2018 · If you run out of oil for your oil burner (or the oil filter is clogged in my case) here are some quick tips to get it running again. It also starts, runs for 10-15 seconds, and then shuts off. wc. I’m new here and I’m looking for some help with my 18 yr old Buderus G115 with Riello burner and Ecomatic HS 2105 control. G115 WS US/CA. The G215 are designed to maximize the heating value of every ounce of fuel and built of the highest quality materials. In this home, we installed a Buderus Logano G215-4 cast iron oil boiler with a Riello burner. Install a fill connection in the supply piping to the boiler. Step 1: Yank the thermostat off the wall. The distinctive Nov 8, 2021 · 4/18/11 I have a Buderus oil Logano G215 US boiler, a Buderus r2107 Logmatic Control , and a Riello 40 F5 burner. FAQs. txt) or read online for free. I also added a Triangle Tube (Maxi Flo 400) heat exchanger for my indoor pool. Jan 28, 2011 · Retired. Apr 18, 2011 · 4/18/11 I have a Buderus oil Logano G215 US boiler, a Buderus r2107 Logmatic Control, and a Riello 40 F5 burner. Installing the boiler 5. Available separately, or part of the G215-7 Bundle. net Security considerations 13S we reserve the right to make changes due to technical modifications! User Manual Logano G215 USA Number 2012/10Buderus Heiztechnik GmbH Security Considerations1. Condensing gas boiler 80 kw/100 kw (36 pages) Boiler Buderus Logano G124X II/SP Installation And Maintenance Instructions Manual. Control device and heating system faults are indicated on the control device display, subject to the control device being equipped with a display. 1 Safety Considerations. If you did not fill and purge the system properly after changing the circulator you may have had air in the system causing the Low water cutoff to trip. Logano G115 WS US/CA – 6 720 804 873 (2012/10) General safety instructions and explanation of symbols. I pushed the red lit button on the burner and it started; I had hot water for about a week. This morning, it did its "start/stop" about 5 times between 4:00 a. Il giusto combustibile. We have 3 Buderus Logano G215 US manuals available for free PDF download: Installation And Maintenance Instructions Manual, User Manual. Fix 1: Clean the buttons. Ecostream cast iron boiler output range from 86 kw to 1200 kw (80 pages) Boiler Buderus Logano GE315 Installation And Maintenance Instructions Manual. Perhaps in setup () turn the pin 13 led on and delay 2 seconds, then turn it off, and do nothing in loop (). Yesterday the 10Amp/250Volt fuse on the BLog r2107 Control did its job, is dead and I read more Feb 13, 2016 · Please read these instructions carefully 6 720 804 877 – 2012/10 EN-US For the owner/operator Users Manual Oil and Gas Fired Boiler Logano G215 US C 2 We reserve the right Re:Reset button not working. The Buderus Logano G215-4 also comes with an unbeatable warranty, meaning that this manufacturer stands by its products. Caution! Observe the safety instructions of this. Boiler Buderus Logano G215 US User Manual. and 13% CO2. 2 Application Purpose The boiler can only be used for hot water space heating Jan 13, 2010 · Hello; I have a brand new Buderus Logano G215 boiler here in our farm house. Based on what your reporting you may have replaced a perfectly good circulator pump and expansion tank. Switch the ON/OFF switch on the control to OFF (position "0"). I purchased this unit for my shop and never installed it so it is time for it to go. Cast iron sectional boiler for oil or gas pressure jet burners (52 pages) Boiler Buderus Logano GE515 Installation And Maintenance Instructions Manual. I bought this house which had been vacant for about 12 months and had about 1/8 th heating oil in each connected Roth 250USG tanks in the mechnical room. Edited below: The reset button means there is a problem with the flame sensor. Includes B-Kit comprised of burner mounting bolts set, supply manifold (1-1/2" x Mar 19, 2011 · My Buderus Model G-115 furnace will attempt to start, you hear it come on but it immediately shuts off. TECHNICAL DATA SHEET PRODUCT: Buderus G215 Boiler The safety limit cut-out temperature can be adjusted within the 4000 series controls dependant on system requirements, The maximum possible system flow temperature is the safety limit temperature minus 18k. Heating and Cooling Heat Pump Systems Manuals. Remove the dislodged debris, and that will get the affected buttons working. (68 pages) Aug 7, 2013 · My Buderus Logano G115/4 burner will not ignite. Buderus G215-7 - 256,000 BTU Output Logano G215-7 Cast Iron Oil Boiler w/ Burner- Note: Product Title reflects this boiler's IBR Net Output Rating. Oil and gas-fired boilers (72 pages) Boiler Buderus logamax plus gb142-24 Installation Manual. We have a 2,700 square foot split level home. 1 General safety instructions and explanation of symbols 1. Gas & Oil Boilers and Furnaces Manuals. Fig. 326 posts · Joined 2012. Dirty flame sensor rod: Every now and then, the flame sensor rod gets dirty and shuts the Convert Buderus G215 to gas? Jeremy Scott Member Posts: 12. placing the boiler in operation. <br><br> Note: Although it is pictured, the Buderus Logamatic boiler control is sold separately. Show more. 2 Application Purpose Jan 5, 2023 · 4/18/11 I have a Buderus oil Logano G215 US boiler, a Buderus r2107 Logmatic Control , and a Riello 40 F5 burner. The Aquastat is set to 180 degrees but the digital readout has the boiler temp at 100 degrees and the DHW at 77 read more. Such faults can generally be reset by pressing the reset button on the burner. Page 38: Installing Burner Fit the shut-off valve to the fuel supply pipe. - Answered by a verified HVAC Technician We use cookies to give you the best possible experience on our website. The input when fired on gas is 294 kBTU/H. I reset it to winter mode, read more Conversion kit for 124x series boilers instruction for high altitude (2 pages) Boiler Buderus Logano G215 US Installation And Maintenance Instructions Manual. Buderus Logano G115 WS Manual. Al momento della messa in esercizio l’installatore indicherà, nel Dec 28, 2012 · I have a Logano G215 boiler which goes thru start-stop-restart issues especially noticeable in the morning. Se- cure properly with a clamp. that are described in this manual. Consult with a trusted electrician to understand what options may be available. Dec 1, 2019 · 4/18/11 I have a Buderus oil Logano G215 US boiler, a Buderus r2107 Logmatic Control , and a Riello 40 F5 burner. pdf), Text File (. installation and maintenance manual before. Check the flue pipe for leaks. Includes B-Kit comprised of burner mounting bolts set, supply manifold (1-1 January 2018. Buderus recommends the use of customized Becket AFII, Carlin EZ-1 and Riello F3 and F5 burners when firing G115 boilers with . Change the cable by the Manufacturer. I only have one zone control that is for the second floor. W. Then when the led goes off, you know setup () has finished; so press reset and see if the led goes on for 2 secs (Optimal Valve): __Inc. I have a Buderus G124X boiler with a logamatic control and a buderus storage tank. Make sure to clean the air filters and keep enough vents open so the furnace has enough air to operate and clean the blower wheel as well. %. March 2008. Every time you restart the burner and it doesn't ignite you are pumping fuel into the chamber. Jan 7, 2011 · HVAC Supervisor. The owners have had to hit the reset button twice in the past week. Also support or get the manual by email. New Buderus G215 /7 Waste Used Oil Gas Burner 294K BTU Hot Water Boiler Furnace. This Thermostream boiler is ideal for new installations or as a replacement for virtually any make or model of boiler. 03 in. 1 Controls and heating system faults are indicated on the control unit display if it has one. 2 Switching on the heating system (Logamatic 2000) Set the boiler water thermostat. Note: Although it is pictured, the Buderus Logamatic boiler control is sold separately. Install 5" to 4" reducer on boiler vent connection. G205/G215/G225. 41,423 satisfied customers. 5 1 Correcting burner faults V Press reset button on burner. The input when fired on gas is 350 kBTU/H. Also, scan your PC for viruses with these tools: List of Malware Removal Tools. Sep 28, 2016 · 4/18/11 I have a Buderus oil Logano G215 US boiler, a Buderus r2107 Logmatic Control , and a Riello 40 F5 burner. Operating instructions Logano G215 WS oil/gas-fired special boilers • Issue 02/2006 Page 4: For Your Safety Work on In the following text, the Logano G215 WS oil and gas- electrical and fuel-bearing components fired boilers will generally be described as „the boiler“. Thus treadmill is no longer useful. The Boiler sits on top of the DHW Tank. Carefully measure the required length of vent pipe. Acknowledged as the leader in high-efficiency, low emission hydronic heating, Buderus offers innovative design and quality manufacturing. If these instructions are not followed exactly, a fire or explosion may be caused with serious property damage or loss of life and serious injury. First remove the cover screws. Buderus Developed a full three-pass system to help increase efficiency. <br><br> This Thermostream boiler is ideal for new installations or as a This manual contains important information for the safe and correct installation, commissioning and maintenance of this boiler. Reading the Buderus Logano G215 user manual and adhering to the rules of using the device provided there, greatly help in its effective use. 1 for each of the 3 house zones, 1 for the hot water and 1 for 9. The Aquastat is set to 180. ip oz iy do pp ad ey px vg nc