Stones

Following on from some discussion in my blog: we are experiencing some fan noise transmission through our radial ducting to individual room valves, only really noticeable on normal ventilation rates at night when the house is silent, but certainly noticeable during the day when the MVHR is on boost. Experience of other members suggest a silencer would greatly assist in reducing the transmission of any fan noise, and I'm pleased to say having contacted my supplier (BPC) they are going to send me a silencer. I'm also planning to build my own using some acoustic foam that I've purchased. I'll do a comparison test in due course to see which silencer works best. One of the things Gary from BPC suggested was that there may be an air imbalance in the MVHR unit, and I thought it would be helpful to explore how we all go about balancing our systems. I borrowed and airflow LCA301 meter (with hood) from my builder and used that to measure the air flow at each room terminal, adjusting each individual room terminal as required to meet the flow rates specified by BPC. I know some members have distribution boxes that allow the adjustment to be made by way of restrictor rings in the distribution box. I balanced the system and set fan speeds so that the supply and extract air flow rates were the same. The cumulative supply / extract rates were equal to each other (or at least as close as I could get them to be). However, thinking back to previous builds and advice, and one which was professionally commissioned, there was always a difference in the supply and extract air flow rates of up to 10%. Has anyone else done this? I'm not convinced this is the best approach as you end up over or under pressurizing the house.

Well, I emailed Gary and he responded very promptly. He advised that although they haven't had any sound transmission issues reported, he is going to send me a silencer . He also suggested that the noise may be due to an air imbalance within the MVHR unit. I'll start a topic to discuss this. My acoustic foam has also arrived so my plan is to knock up my own silencer and when I receive the silencer from BPC, test run both to see which is most effective on the supply, and use the other for the extract.

Welcome to the forum. What type of survey did you have done?

I looked at buying mature trees for our last house. There was a trade nursery reasonably close to where we used to stay (although damned if I can find it online or remeber the name). They were prepared to sell to me as I was looking to buy several specimens. The problem was price, to get a truly mature specimen that has already grown to a reasonable size such that it immediately provides the screening you want, we were looking at several hundred (as in £500 or more) per tree, plus transport, plus excavator to plant them. One way round the problem is to over plant the area with younger, more affordable specimens and just accept that you will thin out some of the trees in due course. Obtaining specimens that are already 6' - 8' high is reasonably easy, albeit there won't be much body to them.

Hedge your bets. Three of my former colleagues emigrated to foreign parts seeking a better life, each of them ended up returning with 12 months, either because they didn't like, it, their family couldn't settle, or the jobs they had gone to didn't match expectations. The grass isn't always greener...

References for how height is measured:- In England https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/606669/170405_Householder_Technical_Guidance__-April_2017_FINAL.pdf “Height” - references to height (for example, the heights of the eaves on a house extension) is the height measured from ground level. (Note, ground level is the surface of the ground immediately adjacent to the building in question, and would not include any addition laid on top of the ground such as decking. Where ground level is not uniform (for example if the ground is sloping), then the ground level is the highest part of the surface of the ground next to the building.) In Scotland: http://www.gov.scot/Resource/0050/00502132.pdf When measuring the height of the development on sloping or uneven ground, the height should be measured from the highest point immediately adjacent to the gate, fence, wall or other means of enclosure. In Scotland we also have The High Hedges (Scotland) Act 2013. I believe there is some like provision in England, so worth bearing in mind.

We touched on this before (using ozone as an odour eliminator) following your Chilli experiment. I've still to invest in a generator to try it for myself. On the to do list. I suppose the main question would be how big an ozone generator would be required to remain within safe limits?

It'll certainly be interesting to see if Salmond and Robertson (Angus) get back in - I understand a lot of effort is going into overturning their majorities. I don't think it's been a good campaign for May. I can't say I'm especially impressed with her performance, and the U turn on social care funding worries me in terms of how she will negotiate. I think Corbyn will do better than many think, he is a good campaigner. It's a two horse race up here, Liberal vs SNP, and I can't bring myself to support either, because I detest key policies each of them has with equal measure. Just doesn't feel right spoiling a ballot paper...

My council has just started charging for the service. I managed to get my paperwork in beforehand so avoided the fee. On previous builds, I did as @ProDave has done. There was never any real problem except it seemed to take longer for the address to appear on certain databases.

We fitted a Siemens extractor with re-circulation kit (additional charcoal filters on the fan). We don't use it if just boiling veg on the hob, but do use when frying food or using the grill plate we have for the hob. Judging by the grease that's trapped in the initial stainless steel filter, I would say that they do provide some meaningful filtration and odour reduction.

We used Scotframe for our last house, and I obtained a quote from them for a current house before going down the route of ICF. I certainly found them to be happy to quote for whatever level of package / finish I wanted, were open to more challenging designs and how best to achieve them and were willing to look at changing part of a quotation to reduce costs (in our case looking at alternative ways to construct a vaulted roof space). The actual kit (Valutherm) seems well made and engineered to the exact sizes specified. No issues with delivery either.

I've already ordered the acoustic foam! I'll maybe drop Gary at BPC an email and ask the question if I should have got a silencer, or if as I suspect, they now include one where they didn't before. I had considered buying one ready made but for the same money I can make one significantly bigger (which should provide more sound absorption) plus I'll have enough material to make a smaller silencer for the extract ductwork.

Whilst doing so groundworks the other day, I had to remove a riser from our treatment plant inspection chamber. I took the opportunity to take a quick sample of the treated effluent to see how clear it was and if there was any detectable odour. I'm pleased to say it was both clear and odour free. The treatment plant itself (Biopure) appears to be working as it should, the air pump diffusing air into the central digestion chamber, with the outer chamber topped by a layer of scum which I believe will eventually form into a crust. I'd like to be able to test the quality of the treated effluent, to see how clean said effluent is (and whether the results match the manufacturers stated performance) but I can't seem to find any kits to do this, other than by spending a fair chunk of cash: http://www.camlab.co.uk/palintest-sewage-effluent-kit-p26092.aspx Just wondering if anyone else has self tested their treatment plant effluent and what did they use?

@Nickfromwales It's a dead of night issue - audible noise when the house is otherwise quiet / no daytime general activity. You don't hear anything to speak of during the day unless you boost the ventilation rate (ours set at 55% or circa 250 m3/hr). It doesn't prevent sleep, just something I'm aware of and would like to reduce.

No silencer at present. BPC didn't offer one, and never having required one before, I didn't think to ask. Perhaps feedback has encouraged them to include silencers in their kits? Was this part of your initial order or something extra they sent you at a later date?

BPC, who supplied my unit and ducting, provided the flow rates for me. I've attached an extract of my MVHR plans showing this information. MVHR flow rates.pdf

One of the final significant jobs I had to do before we moved in was connect up and commission the MVHR. All the radial ductwork and individual plenums had been fitted at first fix, however I had left installing and connecting the actual unit until the loft has been insulated, as I didn't want to risk pipe connections being damaged. The day before we were due to move in, the insulation contractor having laid all the loft insulation, I spent a couple of hours in the loft space above our vestibule connecting ducts for the air intake, air exhaust, and the supply and extract ducts to the distribution boxes. I decided to locate the MVHR in our (cold) loft space, primarily to free up space in my service cupboard which houses our DHW cylinder, UFH manifold and CU. The installation manual advises that where the MVHR unit is located in a cold rather than warm part of the envelope it should be insulated. I initially considered lining the whole of the relevant loft area with insulation, but having worked out the cost, and then being able to salvage a number of sheet insulation offcuts from the skip, I ended up forming an insulated box around the MVHR unit. As you can see in the picture, it's a very simple box, the relevant supply and extract ducts simply cored through the insulation. Our MVHR unit is a Vent-Axia Kinetic Sentinel Plus. These can be supplied in either left hand or right hand format to suit your installation. My plans had originally shown the air intake and exhaust on the Southeast roof of the house, but as the house was being built it became clear it would be more convenient for those vents to be located on the northwest side of the house. Making that change left me with a problem of having an MVHR unit with the duct spigots for the internal supply and extract on the wrong side of the unit. Fortunately the Vent Axia units can be reconfigured by taking off the front and back of the unit, disconnecting and removing the control panel, rotating the unit chassis through 180 degrees, then reassembling so that the back is now the front. Having connected all the ductwork, the final thing to do was connect the condensate pipe I had fitted during first fix (which discharges to a rainwater trap outside) to the flexible condensate pipe on the base of the MVHR unit. Having switched the MVHR on, I then went about balancing the system using an Air Flow meter borrowed from my builder. This was a relatively straightforward process and just required minor adjustments to individual diffusers in each room. Our system is currently operating at a normal supply rate of 32% which equates to 150m3/hr. Having measured efficiency during cold and windy weather, it operates at 90% efficiency in terms of temperature differential (room temperature to supply air temperature). In warmer weather, the Summer Bypass, which I have set to come on when internal air temperatures exceed 22C and ambient air is above 10C, automatically activates. If ambient air temperature exceeds internal house temperatures, as was the case last week, the summer bypass remains inactive so that outgoing stale air can cool incoming fresh air (albeit the effect is negligible). As others have found, whilst summer bypass does provide limited cooling of incoming air, it is not on its own enough to cool the house. Cross ventilation by opening windows remains the most effective way of providing such cooling (in the absence of any active or UFH cooling). The final feature worth mentioning is the humidity sensor, which variably boosts the ventilation rate to ensure RH does not exceed the level set in the controller. This also seems to be working well, auto boosting ventilation when showers are used. When cooking, if we deem it necessary, we can manually boost ventilation to assist in the extraction of cooking odours. Overall I pleased with how the system is operating. The one thing I have noticed compared to other MVHR systems we have lived with is the noise of the fans which you can hear through the ductwork. This is the first house where we have used a radial system rather than 150mm main ducts with branches off, so it may be the duct choice, as I can't recall hearing fan noise on previous installations. To combat this issue, I've ordered some self adhesive acoustic foam sheet, and plan to construct a silencer out of scrap MDF and timber, line with foam and externally insulate, to fit between the MVHR unit and distribution boxes. I'll report back in due course how effective this is. The final tweak to the system that I'm considering is fitting a CO2 sensor so that the unit can auto boost ventilation rates as required. Vent Axia want £350 for their sensor which is a non starter, but looking around, the following may be an option as it seems suited to the parameters of the Vent Axia: https://www.digikey.co.uk/products/en?keywords=235-1413-ND Again I'll report back when I've looked into this some more. Next entry - 2nd fix plumbing

I think it's historical. When we did our first self build (and that was basically a turnkey with minimal input from me) 25 or so years ago, self building meant I got a detached house 50% larger than the semi I could purchase from a developer for the same money. It also meant I could have a layout that suited us and the site. We sold that first house in a stagnant market (so developers houses hadn't seen any price increase) and made 20% after taking into account selling costs. Then Grand Designs came along, followed by other programmes, which extolled the virtues and money saving that was possible. Securing a plot became more expensive as more people jumped on the bandwagon. As the bandwagon rolled on, ever increasing land costs and construction costs (many tradesmen that I spoke to were delighted at the way things were going as it enabled them to raise their rates) nibbled away at the margin to the point we are at now in many parts of the country, where self building still gives you a benefit (site you want and design you want) but not the saving / profit. House price inflation masked a lot of the reduction in profit margin for self builders.

@Ian Out of interest, what was your reason for deciding not to install MVHR?

MVHR really is a must. We've lived with MVHR since 2003, and I wouldn't consider not installing it, because the improvement to internal air quality vs a house without is considerable. Heat recovery is a bonus.

We also found ramped access very useful when the kids were young / were using prams or buggies. It's one of those things that when introduced, I was very resistant as I preferred the look of steps, but level access, if thought out and designed in doesn't have to look bad, and can enhance the look of an entrance. I would agree that poorly designed or 'afterthought' ramps can be a bit of an eyesore.

Our ICF blocks were 65/150/65 with an additional 140 externally. Consequently we have quite deep external reveals, the only issue this presented was having to source my own aluminium window cills, which I sourced (powder coated to match the windows) at half the price the window supplier wanted for their cills.

I've just been chatting to my neighbour who is going to be constructing a retaining wall along part of our mutual boundary - same requirement, ledge required to form part of overall strength of the retaining wall.

In our last house we had a low flow temp oversized radiator based system, master thermostat in the hall, thermostatic valves on each radiator. We ran the house with all radiator valves open for an even temperature, but did on occasion turn off the bedroom radiators. Doing so usually resulted in a 1.5C to 2C reduction from the set house temperature.

The Mitsubishi Ecodan that I have has a cooling mode which can be activated by changing a dip switch in the control module, and can then be programmed / operated from the main controller. The manual identifies both the dip switch setting and the control menu tree. Just have to get round to trying it... . Tags updated for future searches.