Wonder why the MPV makers didn't just use a additional £10 relay to give a guaranteed unpowered (HW) last port of call and a very long MPV life, no good for their balance sheets though.
Open vented system, No HW, CH works fine, BAXI 80HE boiler shows Dry Fire after every restart
- Thread starter fandyman
- Start date
Wonder why the MPV makers didn't just use a additional £10 relay to give a guaranteed unpowered (HW) last port of call and a very long MPV life, no good for their balance sheets though.
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Ok I repeated this test too now to make sure the boiler was still being fired when I switched OFF for CH (HW still was ON) and the boiler and pump did not switch off this time and continued firing. The pump showed 19 W.
Whoever advised this clearly hasn't a clue in fact needs a Y plan valve shoving where the sun don't shine,
As Madrab has advised S plan is far superior and suffers far less breakdowns and is much easier to diagnose faults.
If we find a faulty Y plan valve that requires a drain down to sort we convert to S plan using eph valves with 5 year warranty.
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Indeed - It didn't really seem to make sense to invent a convoluted but never the less very clever process to ensure the valve performed the way they wanted depending on what permutation the system was at but as you suggest there must have been a longer term financial servicing factor involved whereby the actuator failure was almost guaranteed and would require replacement.
OK thanks for your patience, IMO,(again), I don't think there is anything fundamentally wrong with your system, possibly the MPV might be mechanically worn and changing positions with a pump running at a 6M head on full speed is causing problems, you can run for the next few days anyhow at CCII (3M), if no problems, consider changing pump mode to CP2 (4.5M), again if no problems, increase to CCIII, 6M head, again if no problems I would be quite happy to settle on CP2 (4.5M).
What initiated this most interesting Saga was I think. you said you run with both HW & CH selected, the roomstat, located in the hall was probably never satisfied, no problem as long as long as TRVs not throttled too much because each time the HW was/is satisfied the MPV changes over to CH only, but when the TRVs throttled down or you shut them then little or no flow, correctly triggering the boiler DRY FIRE alarm and cut out.
I set everything back to how it should normally be - room stat 20C, cylinder stat 60C both CH and HW ON on the progammer and the pump pumping at CCII 18-19W and report back after a while how it goes.
What I noticed so far is with the pump setting to CCII I notice some rads are not as warm or take longer to get warm but I am OK with that if the system works now.
I wanted to say a big thank you to all of you guys as without your help I would probably be few hundreds off my pocket and more clueless than before. Thank you for your patience guys!
What I noticed so far is with the pump setting to CCII I notice some rads are not as warm or take longer to get warm but I am OK with that if the system works now.
I wanted to say a big thank you to all of you guys as without your help I would probably be few hundreds off my pocket and more clueless than before. Thank you for your patience guys!
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They did solve it, with a MOMO type 3-port valve, which only moves position, when called to move, the rest of the time, it sits unpowered.
Why.
Combi every time is for those who cannot configure a heat only boiler
CCII is only giving you ~ 9.2LPM at 2.9M, with both HW&CH requiring heating together then won't be great so I wouldn't waste much time leaving it there as I can't see CP2 at 4.5M causing any problems, you should get ~ 11.5LPM at ~ 22W on that setting.
You can get 50kw combis now. They work fine as long as flow rate is ok.
Really?
This is a boiler model I regularly work on same as combi boilers
This is bread and butter work for me.
When I say a heat only boiler is way to go along with cylinder, I say that from base of experience
If boiler in the post is a nightmare, to repair a combi when it breaks down is going to be suicidal
To repair a boiler one needs to understand operate sequence, need set of tools and skills to work on gas, water, electrical, mechanical and electronics. Being able to join two pipes and hang the boiler on a bracket does not means nothing.
When it comes to a gas boiler, a boiler should be chosen by looking at each site. One boiler make and brand or type does not suit every household
Can see page 10 just round the corner
@Johntheo5 I've left it on CCII for 2 days now and no problems so far (my wife will kick me out from the house if I go to the loft again ).
Will try to check tomorrow though.
).Will try to check tomorrow though.
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