Alternatives for HTP Vision 2

gurs

I have been advised by HTP that the main board in a Vision 2 controller is failing. HTP no longer makes or stocks the Vision 2 or its main board (HTP part 7250P-222), and has no suggestions for alternatives from other manufacturers. I am looking for some suggestions regarding alternatives. Sorry for the long post, but I wanted to provide enough detail for the question to make sense.

SYSTEM OVERVIEW: This is a residence where the boiler provides heat to (1) numerous hydronic radiant loops, (2) hot water coils to two air handlers, and (3) a DHW tank. In total, there are 10 different radiant loops/pumps controlled by 7 thermostats (which all run to a series of Nix relays) plus the DHW loop/pump. The boiler is a 1-year-old HTP Pioneer PHR-199-55, and the zone pumps (other than DHW and return) are all Grundfos UPS15-58FC. The pumps (other than DHW and return) are all wired to a series of 3 Nix boxes containing 10 relays (9 of which are in use). The DHW runs straight to the Vision 2.

VISION 2 CONFIGURATION: The Vision 2 thinks there are 3 zones: DHW, radiant and other. Zone 1 is DHW and has priority, so all other pumps will shut off when DHW calls for heat. There is a DHW temp sensor wired to the Vision 2, and the Vision 2 controls the DHW pump. Zone 2 is radiant, and has a temp sensor and mixing valve on the radiant feeding loop (set to 115). Zone 3 is the fan coil feeding loop (no temp sensor or mixing valve on that loop). Whenever zones 1 or 3 are calling for heat, the Vision 2 instructs the Pioneer to heat to 180-degrees. If only zone 2 is calling for heat, the Vision 2 instructs the Pioneer to heat to 115-degrees. If zone 2 and 3 are calling for heat, the Pioneer will heat to 180-degrees and the mixing valve will keep the radiant loop (zone 2) at 115-degrees.

PROBLEM: The problem was that the Pioneer was not heating beyond 115-degrees. HTP diagnosed the problem as the Vision 2 board (the outdoor temp sensor is reading correctly but when connected to the Vision 2 board the boiler constantly modulated to 115). When the sensor is disconnected from the Vision 2, the boiler will kick to 180 if the DHW or fan coils are calling for heat. I could just keep running without the outdoor temp sensor and just lose the efficiency of the outdoor reset curve. However, HTP advised that when one part of the Vision 2 goes bad, other parts are likely to follow. Sounds like an alternative is in order.

ALTERNATIVES: One alternative would be just stop using the Vision 2 and wire everything straight to the Pioneer. The Pioneer has 2 zones, so I would need to add a relay to bridge two of my current zones. Bridging the fan coil and DHW loops makes the most sense, since both get 180-degree water and run without mixing valves, but doing so would mean I lose the DHW override priority. Or I could bridge radiant and fan coils if I wanted to keep the DHW priority, but then I would lose the ability for the boiler to run efficiently at 115-degrees when only the radiant loops were calling for heat (radiant loop would always get 180-degree heat and rely on the mixing valve to get to 115-degrees). In either case, I’m not sure if I would need to replace my current mixing valve with a mechanical valve or if the Pioneer can control that valve.

Does anyone have any suggestions for (1) possible Vision 2 replacements, (2) ways to make everything work without the Vision 2 or a replacement, or (3) places I might find a new/used/refurb Vision 2 main board?

lchmb

If you use an sr503 to control your DHW and fan coil you could put the water tank on the priority zone.

gurs

Thanks lchmb. If I implemented that solution, wouldn't I lose the modulation benefit of the boiler? How will the boiler know whether I need 115-degree heat or 180-degree heat?

Also, if I went with that solution, could I get the same benefit as provided by the sr503 by wiring the DHW to the spare zone in the NIX box, or does the sr503 do something different than the NIX?

Zman

Tekmar will have some options. A 422 controller would do the job. You would need a zone controller like the 336 to run the pumps. The tn4 stats have some nice features or you could use the ones you have.

gurs

Thanks zman. I talked to a Tekmar rep today. He did some research and told me that I would need at least 3 different Tekmar components to replicate the functionality in the Vision 2. Sounded really expensive and complicated.

FYI, the thermostats are all Crestron.

NY_Rob

Many "main boards" fail because of bad/bulged/leaking electrolytic capacitors. They are easy to identify:


In most cases the bad caps can be replaced for just a few $$ vs. purchasing a new board... if it's even available.

In the last month I've repaired a main board from a 42" LG TV with bad caps, and a ASUS server motherboard with bad caps. Both cost less than $10 in parts to repair.

If you can't find a replacement board- if the old board has electrolytic caps... give them a good look-over they may need replacing.

gurs

NY_Rob said:

Many "main boards" fail because of bad/bulged/leaking electrolytic capacitors

I actually checked for bulging capacitors based on experience with other boards, but no such luck here. Only one capacitor and it is unbulged. Anything else to look for on the board? Here is a pik of the board:

NY_Rob

It looks a little funky in the area of the 5w 160 ohm power resistors... look for burnt traces, and burnt resistor, etc...

gurs

I think it was just the lighting. Here are a few more close-ups of that area.

NY_Rob

Have you verified the operation of the outdoor sensor?

Most thermistors come with a temp/resistance chart- disconnect the sensor from the board, read the sensor with an VOM, check the outdoor temp- consult the temp/resistance chart... the two should agree.

On my HTP boiler the ODR sensor is a simple 1$ 10K Ohm NTC thermistor. The few times I've checked it with a VOM... it was pretty much dead nuts on value according to the temp/resistance chart.

gurs

I don't have a VOM handy. But I have checked the temp reading from the outdoor sensor using the D5 function in the Vision 2, and it shows me the correct outdoor temperature. I assumed that meant that the sensor was working. Are you saying that I should also check the resistance, or if the temp is correct then the resistance must be correct also?

NY_Rob

If the display shows the correct outdoor temps over a wide range- the sensor is working.

FWIW- Going by personal recent interactions with HTP support Techs... I don't really have too much confidence in their abilities to diagnose issues. It seems if you speak with three different techs... you get three different opinions.
It seems like some of them are more like "parts hangers" vs. technicians because they like to get off easy by saying "replace the xxxx and see what happens".

gurs

Yes, I see your point. Honestly, I am shocked that HTP would discontinue a whole product line, not stock any replacement parts and not have researched replacement options for their customers. Not sure how they expect to convince people to buy new products when you know the company won't hesitate to cut you loose if it suits their bottom line.

NY_Rob

Just like other HTP branded products- HTP doesn't actually manufacture the item- they buy it from a manufacturer and stamp the HTP logo on it. Once the original manufacturer stops producing the item, it's marked as discontinued by HTP. HTP has no control over it other than keeping spares for that product on hand.... they probably try to limit that too to keep inventory costs down.

I think all of us that have modern fancy condensing boilers will run into the same issue you're seeing now if we try to get parts for them 10 years (assuming the boiler lasts that long) down the road.

Rich_49

Simple nice fix would be to connect DHW sensor and let the Pioneer power that circ . You could use an SR 502 for your space heating letting the end switch communicate requirement to the Pioneer . Program Pioneer ODR for your high temp stuff and use a Taco I Series ODR for your low temp .

gurs

This system is just baffling me. I cannot figure out how the boiler knows to fire on if the fan coils are calling for heat, or what temperature water to provide. The only thermostat going to my Vision 2 board is for Zone 2, which is the radiant loop, and there are no wires on the thermostat posts for the boiler. It is a mystery...