Our Bunn VPR coffeemaker takes a LONG time to heat up the water. If we don't wait several hours between pots of coffee, the coffee is luke-warm at best. Does this sound like a heating element or thermostat? Is there a history of this issue/fixes? We use distilled water so scaling in't likely a problem...

VPS/VPR are pour over brewers. Like the 12 cup brewers you find at home, they need to be filled with 12 cups of water (a full pot), heated and then peculated over the coffee grounds and collected in a decanter.
BUT there is one main difference! The VPR and similar COMMERCIAL coffee machines are quick brewers. They usually have a pre-heated pot of water stored inside the machine.
* VPR's and similar machines REQUIRE a pre-fill and heating period prior to brewing. This means it's sitting on a level table and filled with water until water sprays from the brew head. At this point the unit is plugged in and the heater is turned on (there may be some water discharge from brew head as the water expands). Ready light will come on in about 15 mins.
* To Brew; Place coffee grounds in filter, place in funnel and brew head, clean empty decanter under funnel, slowly pour one full decanter of water (cold or hot) into brew tray. Do not overflow tray. Allow water level to sink before adding more water. Only fill with one pot as an equal amount will come out the brew head and funnel.
* Make sure the decanters are all the same size. do not mix a 12 cup pot with a 10 cup pot. One will over fill and the other will under fill. Make sure they match (in cup volume) FYI; Thermo Air pump pots are usually bigger than one pot. Typical filling only to 3/4th of the container. (I think most are in 2.5 to 3 liter sizes)
* If your not getting a full pot then the brewer was partially empty. The second brew (if done within the next hour) should come out full.
* If your still not getting a full pot then the water is leaking or is boiling off. Does it always steam from the top? Thermostat is shorted. Unplug the brewer and call vendor for service.
* Final; If your unplugging when not in use. Then follow the Pre-heat instructions mentioned above prior to plugging the brewer back in. If the tank has been emptied at night or dried up after an idle week. Then there is a chance you may over heat and blow the thermal fuse. Or at best have a half pot short brew as the water dried up.
* Note leaving the brewer plugged in without brewing daily is not a good idea. The water evaporates and eventually drys out the pot. Takes about 1-2 weeks but it does blow the fuse(s) and the unit will need service.
* Final; Follow the Bunn set up and care instructions (manuals from Bunn.com for down loading. *FREE*)
Aloha, ukeboy57

This is really a home style VPR brewer (but looks nicer)
if you listen to their video (link below) they mention it has a pre-heated tank of water already in the brewer. This means the brewer needs to be pre-filled with a full pot of water and pre-heated prior to using the brewer. Unplugging this unit won't be a problem UNLESS it was emptied of tank water and not refilled when powered up.
* The unit will try and heat up the tank of water but if empty then just air which overheats the unit then blows the thermal fuse. Call for service.
* The warmer is still working but it's not hot enough to brew frequently as the warmer may take up to an hour to get the tank hot enough to brew or it may not get hot at all if it's own thermal fuse blew too.
* Final; call for service to be safe.
Aloha, ukboy57
https://www.amazon.com/BUNN-Velocity-10-Cup-Coffee-Brewer/dp/B00EAQJCWW/ref=sr_1_1?ie=UTF8&qid=1516431654&sr=8-1&keywords=bunn+nhs+velocity

The bunn VPR is a gravity brew system what you put in if the tank is full is what you will get out. So pour water in until it flows out the sprayhead, then turn machine on, when it heats up fill up a carafe with water (1.9Liters) and put in your filter with water and brew. It is a good idea to pour water in every morning to make sure tank is full especially if you are not using brewer on the weekends.

While this brewer does have a reservoir that keeps a couple of pots worth of water hot for brewing you can get a cooler second pot if you brew directly after. You should hear the brewer heating up after brewing. Try waiting until it is back to temperature before re-brewing. If that heating takes more than a few (3-4) minutes then you probably have a problem with the heating element and the water is only being heated by the "keep warm" heater.

The brewer has not had enough time to reach its operating temp (usually 7 mins after a brew cycle). If that is not hte case then the machine needs to be descaled.

Make a 1/2 pot 50/50 mixture of cold water and white vinegar then run it through the machine in normal brewing fashion. Place a clean filter in the brewing cup to catch the white deposits that are removed. Allow the mixture to cool, then repeat the process several times while using the same filter. Finally, run several pots of fresh water through to work out the taste of the vinegar. Repeat whenever the brewing time seems to be excessive.

You may not have enough water in the tank.
Follow these steps

1. With the coffee pot unplugged, fill your resevoir/tank until water begins pouring out of your sprayhead and brew basket.
2. Wait for the water to finish dripping then plug in your Bunn.
3. Let your Bunn warm up for at least 8 minutes.
4. Run a test cycle with clean water, remembering to use the water pitcher provided for this purpose, while leaving your empty pot on the burner beneath the brew basket.
5. If your cycle completed, and your coffee pot is filled to the desired level you are ready to make coffee.

Remember that these Bunn models have no water filter installed, so, the cleaner the water the better tasting the coffee.

Our Bunn VPR was delivering luke warm coffee. The problem was lime scale buildup on the heating element. I recommend using a cleaner such as Brew Rite or a vinegar solution. If it still does not heat properly, unplug and remove the heating element for cleaning. This corrected our problem.

If it is mold it will be removed by hot water, just cycling the machine a couple of times. If instead is scale , as I think , then it can be removed using a descaler product:Saeco: Descaling Agent Dezcal Box

What's happening is that it isn't leaking, it's boiling over. You need to turn down the thermostat under the top lid. Also, before you brew coffee, add water to the tank and let it pour into an empty pot. Once it stops brewing, let it heat up for a few minutes then make your pot of coffee.