All Activity

OK thanks for comments. The supply pipework is 32mm MDPE mains in, connected into 22mm copper (16mm MLCP tee to kitchen, 15mm copper tee to outside tap) through water softener (currently on bypass), then approx 5m of 25mm MLCP pipe to the cylinder location, final 1m in 22mm copper to the reducing combination valve. I was getting 37 l/m from the outside tap, so I know the mains supply is capable of providing a continuous 37l/m through 15mm copper. So the main supply through the 22mm copper and 25mm MLCP should be providing at least that and one would think 40l/m + into the combination valve. Mains pressure 3.5 bar. Unfortunately I can't change the 5m of 25mm MLCP with its press fit connector at each end, because it runs under the suspended floor which now has underfloor heating installed. Had I seen the MLCP connector bore reduction at the time I would have insisted the plumber put in 32mm MLCP. But that is the big unspeakable secret with MLCP and press fittings. I have seen some Wavin Tigris M5 / K5 press fit MLCP connectors which claim ''The new Wavin Tigris K5/M5 with Opti Flow reduces the pressure loss in the installation due to the up to 50% larger orifice..''. Mentioned them to my plumber who promptly claimed they would make no difference, and proceeded to fit cheaper ones he uses. A lot of trade are not interested in using anything except what is available off the shelf at their chosen merchant. System performance for the customer doesn't come into it - in fact I have never seen a plumber measure a flow rate.

https://www.proair.ie/products/proair-pa600li-2/ That's the one. I just took it apart and cleaned it and pulled out the fans and found some you tube vids to take them apart. The bearings are a common item. No rocket science. Ebmpapst make most of the fan units so something like this will show you.

That could work alright, could i then fix cement board to the compfoam in order to fill the gap on the exterior? Ive never used compfoam so its hard to visulise what i can and cant do in terms of fixing etc. Thanks for your help. Carl

Inverters have overvoltage protections built in. They shut down when the voltage gets too high and there are at least some saying that the limits imposed on inverters are too strict so they are likely to turn off too early. Doesn't mean there might not be problems with significantly excess provision on a local network but the protections for safety are already there. The inverter size limits are I think it's a way to prevent existing installs having to shutdown due to new installs. Given the benefit of solar outside of peak production I feel if these are the reasons they should be reassessed. It's feasible for a standard to be made so that inverters scale back their output gracefully rather than trip off. If that could be done then I'd guess the whole approval process could be significantly simplified (and people would be more likely to install bigger systems that might be limited in peak but net produce a lot more outside the peak).

Exactly. It's very basic school level physics

isn't the export limit more about overvoltage in the local grid, in which case it could be a near-instantaneous issue...

It isn't a combi, it effectively has a thermal store or UVC, within the enclosure with a heat pump.

You are correct but if you read the post carefully you'll see I said half hour block (the standard time slice for the grid). If your export limit is 3.6kwh and you export any more than 1.8kwh (eg 2.5kwh) in a half hour block you have breached your export limit. The half hour time slice means it is much harder to hide any over export with any inevitable lower export periods eg clouds going over sun for 10 minutes and the system is already working at that resolution. If you do this for every half hour slice you can discourage over exporting because there will be no financial benefit and you might get a visit from the DNO.

Have a look at Requirement G3 - they've even got you needing to provide hot water despite always washing in cold! G3. (1) There must be a suitable installation for the provision of heated wholesome water or heated softened wholesome water to: (a) any washbasin or bidet provided in or adjacent to a room containing a sanitary convenience; (b) any washbasin, bidet, fixed bath and shower in a bathroom; and (c) any sink provided in any area where food is prepared. Whatever next!

Isn't the key problem for any "combi" heat pump going to be defrost and oversizing? For a combi type water flow you need 25kw or so output. With a gas boiler, that's trivial and can be modulated down to 3 or 4kw for heating. Getting a continuous 25kw from a HP means you need more than 25kw to allow for defrost. Such a HP would be large, expensive and struggle to modulated down. Anyrhing else is just a variant of a thermal store or unvented cylinder.

Adding a cold mains accumulator will make a huge difference, for stabilising what you have. Or…. …this. Having small bore pipework between the stopcock and the UVC control group is very impactful on performance, but so many plumbers ignore this; probably some just don't realise it is of such importance. Adding an accumulator can be quick and simple, if you have space for one, and guarantees results. I’ve fitted loads over the last 20+ years and always had great results. Beefing up the control group from 22 - 28mm won’t do much tbh, and I've had lots of UVC’s on 22mm that will do 2 showers simultaneously, where the property has a very good incoming cold mains, so I also doubt that is worth the investment. As always these things are hard to comment on without being able to see the system and survey it properly.

Midsummer, the PV people, have put £250k into the company. I worked for a small wind turbine manufacturer a long time ago. Part of the investor conditions was that they had a patent on their design. Gave the investor something to sell when it all folded, which it did.

... thanks, this matches the builders preference to spray then touch up. 👍

Yes, but the combination needs to be inventive. Adding, say, a lock to an enclosure isn't ever likely to be inventive given how ubiquitous the principle is.

Yep, spot on. Thanks for the link. I completed an installation last Autumn where the old house had 600mm walls completely uninsulated but had been extended with some new walls insulated. This property is heated absolutely fine and the owner says they've never been as warm and comfortable in the house. There's has a 9kW heat pump with calculated heat loss of 6.9kW and I took out a 32kW combi. Interestingly it did take 2.5months for the fabric to warm up - the weather comp curve was a bit all over the place and then suddenly it just settled down to run smoothly. I have used heat loss data derived from studies by some different organisations like Society for the Protection of Ancient Building etc. and recently BRE published updated tables for the calculation of stone walls etc. which bring down the u-values quite significantly. At the end of the day it is simply about the balance between heat in - heat out and the correct means of distributing it around the building, and if you get that right any old building can have a heat pump and benefit from it.

I thought that the idea of any patent followed the basic creative principle that novelty flows from the particular combination of non novel (existing) ideas. It's the way human creativity works - by combining things we already know in novel ways. All patents are just novel combinations of old ideas.

Once its mist coated it will show the imperfections and cracks easier. I'd do all the filling or caulking after that. I wouldn't be dremelling any cracks to make wider. A wet easi fill mix is pretty fine seems to get in cracks ok.

We were told by a neighbour with some glee during our house-warming party (previous house) that the occupant had died in the main bedroom. Luckily there was no smell by the time we moved in!

This is probably a stupid question, but that doesn't normally stop me so here goes... Plastering is done and it seems pretty good I think, but there are the dings and cracks in the usual places. We will be getting the place spray painted as soon as SWMBO can decide a colour. Would it be sensible to fill in some cracks now before painting, or (as builder suggests) do this after the place is sprayed. Is the raw plaster too absorbant to repair before painting? Most of the cracks are only hairline, this one about 1 mm is the widest. A few dings where trades (and myself) have bashed into the walls. I read somewhere that cracks should be dremmeled wider and then flexible filler used, is that a good idea to treat the few bigger cracks?

I see them and fix them all the time. Like I said above, it's unlikely your multi-bloc, but the supply pipework to the uvc that's the problem.

I am talking total combined output there - that is Hot Flow + Cold Flow. If it is Christmas and I have family staying - say every year for the next 15 years. Then you have 6 adults in the house, maybe 2 or 3 grandchildren. You want to run 2 showers at the same time. Someone is running taps in the kitchen making breakfast, someone just put the washer on, and someone flushes the loo. So if the system can't handle it, someone is getting a bad shower, and you are into shouting round the house about who can use a bathroom or ensuite. At present the highest simultaneous output I am getting is 34 l/m combined hot and cold downstairs - that is 17 l/m each for hot and cold. Hot flow and cold flow are not separate, they all come through one input pipe and combination valve. I am only getting more like 20-24 l/m simultaneous combined on other outlets. I don't think this is unusual, part of the selling point of UVC vs gravity fed is the ability to run two bathrooms etc. My mains supply should be capable of 40 l/m+. Are we really saying there is no-one here that has ever seen flow problems with a domestic system regardless of how it is plumbed.

Sorry, the current distance is 475mm, not 350.

I used this mob.

9 a locking mechanism - not really novel. 10 mesh grilles, been used in industry for years to prevent small fingers and animals away from things they should not touch 29 plenty of people have installed a DHW cylinder in a shed outside 30 a modular enclosure novel - no 34 - 36 Here something someone invented about 11-12 years ago - Unical Gas boiler version ASHP version

The EV pre pressure should really be set up by measuring the dynamic pressure with a good flow through the cold taps, (to give say 15/20LPM) after the PRV valve or attached to a (cold) tap fed from the balanced cold on the valve set, which yours are, the prepressure should then be set to say 0.2bar below this, this keeps the diaphragm from bottoming out in any circumstances and also positions it better inside in the EV, IMO. This is probably what happened when the pressure was reduced. It can result in a slightly higher final pressure after a full reheat but this should not be a problem especially since you have a 22L EV on a 252L UVC, If the precharge pressure was 3bar then, after a full cylinder reheat to 60C, the final pressure will be 3.93bar, if the dynamic pressure is 2bar and the EV prepressure is set to 1.8bar then the final pressure will be 4.48bar, a little higher, but not a problem and just may cure noisy operation. I advice(d) the few people I know with UVCs to size the EV to 10% of the UVC capacity and set the prepressure to 2bar anyway even if the dynamic pressure is 3bar.