John Rumm - VRC 470F - HomeOwnersHub

H

Harry Bloomfield 7 years ago

My usual server is off line, so I cannot find the original thread..

Today the VRC 470F was delivered, so I got stuck in a removed all of the old controls and fitted the VR 65 and VRC 470F - this after getting house and water to a good temperature, in case it took longer than expected.

I had it all ripped out and new back in, within 3 hours. CH was obviously working fine, but not so sure about the HW side. CH now runs much more gently, modulates output down to minimum instead of the near flat out or off as before, boiler never seems to exceed 50C, so well inside condensing range.

I had VRC 470F running on its batteries for several hours, without the boiler etc. powered and it retained it time and date just fine. Maybe because the clock is in the 470F and is maintained by the batteries, your 470 has no battery rather it is powered from the ebus. Power the boiler down, no ebus power, clock is lost, but the settings are in non- volatile memory?

The HW issue...

I configured the boiler to assume a mid position valve, but it seemed not to make any difference other than the boiler then allowed me to set a max temp for the HW, but only a max of 50C. Before changing the control system, I was able to set a max boiler output temp of 75C.

470F Menu> Installer Level> System Config.> seems to suggest a Flow Temperature Target 40C, though I have seen this show 51C. It does not allow it to be changed..

There was a 'desired HW temp' setting in the 470F which could be set to a max of 70C.

I initially had the HW running on its cylinder stat. and it never seemed to try to heat the HW, maybe because it was already well over

50C, but I never saw the valve move at all.

I then swapped from stat., to the NTC sensor. I was than able to see the HW cylinder temperature on the 470F, it seemed to be just maintaining a constant 50C, but not much HW was consumed today so I cannot be sure, but I never saw the valve move to HW or the mid position. Except by pulling the NTC out of the cylinder insulation and allowing it to cool, did cause the valve actuator to move.

HW Boost didn't seem to do anything.

I wonder if the legionella setting, once per day might overrule the boiler, if it is the boiler holding the temperature down.

I set the clock deliberately 5 minutes fast, to see if the DCF77 receiver corrected it, as there doesn't seem to be any indication of reception. It hasn't corrected it yet, maybe over night reception? That is probably in the remote outdoor sensor and the 470F is showing the correct outdoor temperature.

For anyone interested - Boiler is a Vaillant 418 ECOfit Pure, valve actuator is a Sunvic SDM 1901.

Vaillant have been downright unhelpful (three times), when asked if the VCR 470F + VR65 + my boiler would work properly together. It seems they do, if I can solve the HW issue.

Vote

J

John Rumm 7 years ago

I have been a bit "off line" myself - flu, and possibly the real thing rather than the "man" variant!

Yup that sounds like its doing what it should.

Yup, no batteries on mine...

The flow temp should just reflect what the "system" is calculating is the ideal for the circumstances (external temp etc). So you don't set it directly. If you play with the Heating curve then you can influence the slope of the mapping between target flow temp based on outside temp.

IIRC the thing comes preset to a curve of 1.2. That would mean with a external temp of ~5 deg you would see a max CH flow temp of around 50 (if you have the internal temp set to 20 - it will alter the flow temp in response to the actual temp demanded as well).

Depending on how good the house is thermally you may need to tweak that.

That basically gives priority to HW generation even if you have the DHW programmed off at that time. However it will only fire the boiler if it sees the cylinder below set point, then once its reached set point it will revert to its normal programming.

I have mine set to 60 for "normal" and 70 for the once weekly cycle.

The CH temp ought not affect the DHW flow temp - for weather compensation to be practical its got to be able to run different flow temps for DHW since it would otherwise only be during fairly server weather you would be able to adequately heat the water.

Vote

G

Graeme 7 years ago

My first thought on seeing the subject was Crikey! Someone has bought an old car and found John's details in the log book :-)

Vote

H

Harry Bloomfield 7 years ago

Harry Bloomfield submitted this idea :

Correction...

The actual boiler setting (on the boilers LCD) were 75C for CH and 50C for HW. Both set on their max.

This morning the cylinder temperature was showing 44C, so I tried the Boost setting. That seemed to raise that temperature to 47C.

The 5minutes fast on the time, didn't correct itself, so maybe it lacks the DCF77 receiver.

Get well soon!

Vote

H

Harry Bloomfield 7 years ago

Harry Bloomfield brought next idea :

I have still not solved the HW issue, but (too) early this morning the CH came on and brought the house up to temperature. I then found the

470's clock was showing 22:30 05/05/19 when the CH ought to have been on. My best guess is that it is actually fitted with a DCF77 receiver and maybe received corrupted data from DCF77 changing the time and date to the wrong data. Nothing else was corrupted, you would have thought they would have done a check sum on the received data?

Vote

T

Terry Casey 7 years ago

There is no check sum but there are three parity bits, one on the minutes, one on the hours and one on the day/date data.

formatting link

Vote

J

John Rumm 7 years ago

Thinking about that, with that plate is would have been registered the year I was born ;-)

Vote

H

Harry Bloomfield 7 years ago

Well I knew that, I just class it all as a 'check-sum'.

The clock's data became corrupted a second time too, Sat/Sun.

I carried out some more tests yesterday, on the HW heating, setting it run a legionella cycle. That caused the boiler to run 85C, which raised the HW a few degrees above the 50C, but the SDM 1901 actuator then began cycling. Radiator/house temperatures increased due to this valve cycling. So my best theory now is that the VR 65 is not compatible with a Sunvic SDM1901 actuator, but Vaillant offer no clues as to what actuators it should work with - they just state a 3-port mid position.

Vote

G

Graeme 7 years ago

Thanks John. Now I feel *really* old :-)

Vote

H

Harry Bloomfield 7 years ago

I managed to get through to Vaillant Trade Tech. They assured me that the VR65 is compatible with ALL makes of 3-port mid position valve actuators. I thought there were some differences?

The also said to ignore the flow setting for HW on the boiler, it only applies when it is a combi type, but it is common software.

I tried my spare Sunvic 1901 and got the same result. Fine on CH, on HW it seems to dither about and chuck heat at the CH circuit.

Sunvic SDM 1901 works as below..

Blue = Neutral Make orange live = HW Only Make White + Grey live = CH Only Make White + Orange live = mid position HW + CH There are two mid positions.

Orange live signals boiler/pump to run. Actuator is a momo, only rotating in a single direction under motor power until it achieves position.

Is this the same as Honeywell's 3-ports?

Vote

B

Bal 7 years ago

replying to Harry Bloomfield, Bal wrote: Hi, what system diagram setting did you use. I have a vented system and originally had it on 1 when I fitted a couple of months ago it started playing up today giving me a heat generator not found error. Only noticed when the house became really warm and despite the thermostat being at the target temp the heat continued. Had to do a power down. Many thanks

Vote

John Rumm - VRC 470F

Join the Discussion

Didn't find your answer?