Posted by: @keithb

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Could write so much more.!!

Then please do so! It will add to the body of information here on the forum. And we may even be able to suggest ways in which you might be able to reduce running costs. Don't forget to include the basics, size and type of property, its heat loss, emitters (rads or UFH), any separation (buffer, low loss header, plate heat exchanger) if present etc.  

Hi 3 bed bungalow epc rated A no recommendations to improve. Changed A glow worm bolier 15 yrs old for bosch compress 2000 awf 6kw. Two radiators were upgraded to doubles in dining room and bedroom as they faced coldest side. The flow temp is set at 50 as when 45 it couldnt cope to heat house and hot water. After researching i moved the internal pump to 2 instead of 1. That definitely helped. The heat pump has a “shield” i made to stop dust and rain so keeps really clean. Area protected by a tall accoustic wooden fence so no strong winds all clearances correct. Loft is probably double the insulation required. The temp is set at 19 at night then 20 between 0630-0830 then 21 0830-1530 finally 22 1530 to 11. Water heats 0530-0730 1230-1330 2230-0030. The settings now provide reasonable heat for house and hot water needs. We are both retired so home most of day. Curtains shut at 1600. We have 4kw solar and 9.6 battery set up but promotors of heat pumps say got to have solar well i have app and the heat pump draws mostly mains as lets face it winter sun means minimal generation. We have solar controller that heats upper cylinder immersion element if enough spare electricity. Water temp asks for 50 degrees. From mid april to mid october solar provides all house hot water so heat pump idle mode. Re rad ratings not sure but original surveyor (had 3 different) said much the same change two. One said 10kw other two 4-5 so they put in a 6. I tried to get a heat geek guy to give me independent opinion but no one wanted to get involved hence why if anyone asks me about heat pumps i say if you really must go with company that guarantees install and performance plus offers long warranty and definitely offers annual full system servicing. I was given bosch pump and telford immersion. Found Bosch wouldnt service only heat pump even though i ordered through them. I paid bosch to come out after 6 months to check over as not happy all issues i had had. That said bosch techie help line spent hours with me on the phone 3 times to get settings ok. Thats when i found they only service the heat pump not the telford or other bits. I had system flushed in december as air valves blocked and rust in water. Kept getting error 08 flow alerts. Cleaned heat pump filter for third time plus they added fernox F1. The temperatures i quoted are mist recent settings. As we were cold they had been 1 degree higher in day. The system is stable at tge moment but as the air valves leaked couple of times i check twice a day now. I dont find the Telford tempest immersion holds the heat as well as our old think it was sadia or similar name. Its a 170 ltr old was 150. Fine fir us as no baths in bungalow plus whole bungalow has full water softener. I am certain rust was from the heat pimp as when first delivered it wouldn't work and Bosch had to come and. Change pump as it was rusty. It was made in july23 but only delivered and installed new jan/feb 25. Think its a known issue. I enquired if it could be changed for a non rusting type like lowera but told it would invalidate warranty. If you have any ideas really appreciate as its been a nightmare

@keithb — thanks for the details, you have covered most of the important ones. I take it from what you've said you don't have any separation between the heat pump circuit and the radiator circuit (and that's how the rust get through)?

The first observation is that it seems you are running on external thermostat control with a fixed flow temperature rather than weather compensation (where the flow temperature is set by the outside air temperature). The latter is generally more efficient, sometimes substantially so. Can you have a look at your heat pump controls and manual and see how to set up weather compensation, if you haven't already done so?

Secondly, I don't like the sound of the rust at all. Do you have any links to it being a 'known issue'? You had the system flushed in December, and it is still rusty? The rust is in fact at least two problems: one, where is it coming from and two, what damage does it then do? 

Thirdly, it is possible that what you have set up to protect the heat pump may also be restricting it a bit, by reducing air flow. Can you post an anonymous photo?  

Thanks so much. Re rust insider at bosch told me not unknown. Apparently they make in china test then residual water stays in until installed. The rust is on the main 28mm feed from the heat pump. Indeed met a designer who told me because of this known issue they now specify lowera pumps as design is none rust. Indeed even the antifreeze valves on the 28mm feed from the heat pump corroded and i had then changed. Tried to picture

re enclosure bosch have seen and were so impressed took pictures to make fir their own at home. Loads of air flow clearances exceed install regs.

i think you are right sbout climate settings. I changed some under bosch tel techie guideance but after bosch service call they said left heat pump off (july 25) when i tried to get heat in october had notice on controller said climate settings on continue yes/no. When i said yes couldn't get going so eventually said no and it ran ok. Going to try and add pictures of enclosure and the antifreeze valve. I would pay to have someone come and check sll my settings but cant get anyone? The bosch book isso thick waded through it so many times niw. Ps there is a magnetic filter internally but not convinced it is effective i have a better one ready to be fitted but waiting to see if the fernox has dine its job re rust. When flushed rads water were pretty clear from 4 different points but the 28mm heat pump feed was orange as was the littke gauze filter on heat pump

Posted by: @keithb

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Thanks so much. Re rust insider at bosch told me not unknown. Apparently they make in china test then residual water stays in until installed. The rust is on the main 28mm feed from the heat pump. Indeed met a designer who told me because of this known issue they now specify lowera pumps as design is none rust. Indeed even the antifreeze valves on the 28mm feed from the heat pump corroded and i had then changed. Tried to picture

Unfortunately this is all too common these days, buy a reputably European brand only to find it is Chinese in all but name. I bought a Webb (once a well known and respected brand for those who don't know) mower not so long ago only to find the whole thing is effectively Chinese with no usable UK support or spares. At least Bosch haven't gone that far.

When they put in a replacement pump, was that like for like, or was the replacement the 'no rust' one? Or maybe the problem is there is still residual rust lurking in the system from the previous pump. A good very thorough power flush and/or system cleaner might help with that. As it is a 'known defect' I would tell Bosch I expect them to pay for it.

That said, I am not entirely sure what to make of the antifreeze valve corrosion. Normally the presence of rust should not cause brass to corrode, unless there is some weird chemistry going on. The orange water in the primary feed from the heat pump but not on the rads is also a bit of an anomaly. Can you add any photos showing the actual damage to the antifreeze valves that might help make sense of what is going on? 

Note that Fernox F1 is an inhibitor/protector, not a cleaner. There are other Fernox products intended to be used as cleaners. 

Posted by: @keithb

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re enclosure bosch have seen and were so impressed took pictures to make fir their own at home. Loads of air flow clearances exceed install regs.

Agree, it's fine.

Posted by: @keithb

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when i tried to get heat in october had notice on controller said climate settings on continue yes/no. When i said yes couldn't get going so eventually said no and it ran ok ... I would pay to have someone come and check sll my settings but cant get anyone? The bosch book isso thick waded through it so many times niw.

That certainly seems to confirm it is not running in weather compensation mode. Incomprehensible manuals are all part of the heat pump world. Can you post screen grabs of any pages that might be relevant, or link to where we can view download your manual? We might (or might not!) be able to spot something relevant.          

Re flushing they did run with F3 fernox first think they tried really hard to cleanse the system after all issues i had had. I thought strange where rust was. First hp kept int stopping error code8. So i cleaned the gauze filter. It was real orange little bits of rust coloured debris. Then i saw the antifreeze valve on same 28mm leg weeping water real rist coloured too. This was begore flushing. Re pump change yes Bosch changed like for like. I know the name quite common begins with W. I think your right i should write to Bosch about it. Manuals are downloadable from worcester bosch web site. I am hoping that rust problem goes now inhibitor added. I think installer forgot because cant see why rust if inhibitor in it originally. I asked the question but got no answer. One suggestion was as bosch service left hp off water stood for 3 months and pump rusted? I worry that many women indeed-non technical men would really struggle. At outset apart from faulty new HP i had wrong wiring leaks oh wont bore you. What doesn't help either controller in back of airing cupboard so really awkward to reach and run through settings. Tried to show the valve will add another picture of the air bleed vslve that also leaked. It is also on the main 28mm feed the concrete flooe is all stained dark orange.-

Posted by: @keithb

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Manuals are downloadable from worcester bosch web site.

I've just downloaded the relevant manual (just to confirm, Air to water heat pump Compress 2000 AWF) and looking at the wired controller instructions, it looks like it is a Midea clone. I am all too familiar with these units because I have one! Even the password to get into the hidden FOR SERVICEMAN settings is the same, 234. And now, looking at your photos of the unit, I can see the resemblance in outward appearance.  

There are two things you have to do to set up weather compensation. The first is to set the weather compensation curve settings, the second is to turn on weather compensation. The former is behind the FOR SERVICEMAN menu, where you need the 234 password. These are the instructions from the Freedom heat Pump Midea Installation manual, starting at the point where you have got into the FOR SERVICEMAN menu using the 234 password:

The chart on the right shows the idea, you are setting the left and right hand ends of the 'curve', along the lines of when the outside air temperature is this, then the flow temp should be this, for each end of the curve. As the outside air temp goes up, the flow temp goes down, the aim being to maych the heat pump output to the properties heat los at each outside air temp. Note that the suggested flow temp settings are just a starting point, you may, or rather almost certainly will, have to tweak them, depending on how your property responds. Also note that at least for now, to do the setting up, you want your heat pump on all the time (which is in fact the standard way of running them). Back out of the FOR SERVICEMAN meno and confirm the settings when asked. Note this will turn off DHW if it is currently on, you have to manually turn it on again.

The same settings are in the Bosch manual, page 84 of the copy I have, but are less comprehensible and less pragmatic.

To turn on weather compensation, follow the instructions in Section 9.13 of the manual (get there going from Main menu > Default Temperatures), setting the line that has HEAT MODE ZONE 1 in it to ON and then select the climate curve 9, which is the 'custom' curve, ie the one you set above, and then back out/confirm as needed. Note that once you are on weather compensation, you can't set the room or flow temp, that's the whole idea, you leave it to the weather compensation to do these things. It looks like the Bosch wording is very slightly different to the Midea wording at this point, I have tried to use the Bosch wording.

Let us know how you get on. If you get stuck, post back with photos of where you got stuck.     

Posted by: @keithb

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Tried to show the valve will add another picture of the air bleed vslve that also leaked.

That does look like possible rust staining, and rust does tend to be a very persistent stain, but the brass looks intact to me where I can see it. I think we may find that the rust problem was 'one of those things' which has hopefully now settled. As you have one (or more) magnetic filters in your system, that will allow you to monitor things.

It may be possible to move the wired controller to a more accessible location. It is just a simple box with one cable connection in a standard installation. 

W is probably from Wilo, a very common brand of circulating pump. 

I do agree non-technical owners should not have to struggle with all this. But it is the state of the heat pump industry in this country, something we frequently bemoan here on the forum.