RossMcO

Posted this in a very old post yesterday, but maybe the age of the post acted against but being read. Searching through the forum for advice, I found this old thread which is pretty close to my query but...maybe worth clarifying, if only for peace of mind. Our build is timber frame over steel foundations and is 300-500 above ground on the low side (where the drains will run) and maybe 1200-1400mm above ground on the high side. Our design has a buried waste pipe running the length of the house (~25m) before connecting to the waste treatment plant another 10m or 15m away (yet to be precisely sited). The groundworker has asked if we prefer the waste pipe to be buried, or if he could avoid the access complications of digging and filling the trench around the concrete footers for the steel founds. If we suspend the waste pipe it will go below ground before exiting the footprint of the building. Don't think there is a major impact either way, but is below ground better to avoid risk of frost, or above ground for access/maintenance or other reason? Not a huge deal in the scheme of things, but would save me a couple of days and maybe £1k-£2k. Ross.

Searching through the forum for advice, I found this old thread which is pretty close to my query but...maybe worth clarifying, if only for peace of mind. Our build is timber frame over steel foundations and has a very similar ground profile to that mentioned by the OP. Our design has a buried waste pipe running the length of the house (~25m) before connecting to the waste treatment plant another 10m or 15m away (yet to be precisely sited). The groundwork has asked if we prefer the waste pipe to be buried, or if he could avoid the access complications of digging and filling the trench around the concrete footers for the steel founds. If we suspend the waste pipe it will go below ground before exiting the footprint of the building. The advice above seems neutral to the option, but is below ground better to avoid risk of frost, or above ground for access/maintenance or other reason? Not a huge deal in the scheme of things, but would save me a couple of days and maybe £1k-£2k. Ross.

Thanks everyone, omitting the doorstops at either the top or the bottom of the frame makes sense...and had often been mentioned in various discussions, old houses manage this naturally as nothing fits tightly anyway. Cheers.

Thanks John, Humidity activated trickle vents make sense. If we didn't skim the doors, then I guess the airflow from the MVHR supply would stall, as there is no escape for the added volume. In most cases the bedroom doors are offset to the main room by a short corridor to allow cupboard access, so yes, maybe I'm overthinking the acoustics aspect. An alternative to the skim on bathroom/shower room doors would then be a vented plate or louver, I guess. Thanks. Ross

On the topic of 5-10mm clearance at the bottom of internal doors. One of our concerns in our build is good acoustic performance - we've always lived in old buildings with good soundproofing between rooms. We have specified no trickle vent windows, extra acoustic insulation between rooms, acoustic plasterboard, etc, and will have MVHR, but I'm trying to understand why 'cross room' ventilation is required, and how you can manage the acoustic penalty of non-sealed doors. Each room will be supplied with air from the MVHR, with extraction in the wet rooms, so is there no way to avoid skimming 10mm off of tightly fitted doors? To further declare my perspective, trickle vents seem archaic to me as well...why spend all that money and effort to build high specification window frames and then drill holes in them? Ross.

@JamesP~Thanks James, Vortex hadn't made my list until you mentioned them. For the others, and to keep you all up to date, I'm trying to get in touch with the company that the architect uses for SEPA calculations, so far haven't had a response to email, but will keep on at them. From their web-site, they seem to be Kingspan reps, so that might go some way to explaining their recommendation. I think all of the systems will do the job, and the majority of the cost is installation (at least in my location and with the quotes I have) so it's not really an economic decision. I favour the aerator system whether from Graf, Marsh or Vortex might end up being as much to do with local supplier and support as anything else.

For 'tiny', I'm reading 'low' use. The challenge is that while there will be empty periods, there will also be periods of potentially full occupancy, so up to 8 adults, plus any weans that emerge in time. That will drive periods of heavy usage, so we will need to size the system to cope with that while trying to make sure we avoid issues related to low flow periods. @Russell griffiths's experience seems to be that it isn't such a major issue, and I'll have other things to worry about more. 🙂

Thanks Russell, that's a very helpful data point. To @SteamyTea's additional fluid question - this also seems rational to me. Maybe I could have someone go in and flush everything a couple of times once a month or every couple of weeks, or try and rig a system to run water from some source or another periodically.

@Russell griffiths perhaps, and I applied little critical thinking to the comments from the supplier, but...he wasn't buying or selling, all servicing would be from a third party, so he was a relatively honest broker. My situation at least initially will be complicated by long absences, and having confidence that I won't arrive to find a non-functioning system has value. Also, I suspect he was overestimating the dosing required, as if there might never be any use, rather than occasional longer gaps. So maybe one cartridge per year, and an inspection/pump out as needed. Do average users normally have a service contract to cover inspection and any maintenance needed? In general though, I agree with you - I'm starting to get a better appreciation of the complexity, or lack thereof, of the different systems. Simpler is better, fewer mechanical parts better than more, simple service access better than in tank components, no electricity better than power being needed. But, beyond all of that, the real life experiences of the community carry most weight, and at least for the active posters on this topic, aerated systems seem to be much preferred. Ross.

Hoping to have PV, but will need another building for that, as our monopitch roof is north facing. National Park rules prohibit any new structures without explicit permission. Consensus of the discussion remains on the aerated system. Cheers.

Completely agree on his contribution - tremendous benefit. Touch wood, I don't have that problem (as of now) but what a fantastic shift of the accepted wisdom.

Have to say, I'm closer to @Alan Ambrose on this one, versus the extreme option of distilling and potentially drinking your own 'liquor', I believe one of the technical terms to be? But, Barry Marshall got a Nobel prize for his work, so @saveasteading and @SteamyTea should be at least worthy of something similar on successful conclusion of their experiment. 🙂 Photographic/video evidence required mind... Back to reality. On the topic of longevity, I guess you could just pre-purchase the bags for the next load, and give yourself ~20 years of service. Depth might be an issue - our site does slope downwards to the water course, but more work would be needed to figure out whether we have sufficient gradient to accommodate outflow to the tank, and then another 2m to the outflow from the tank, and then sufficient drop to the water course. An earlier topic the forum discussed running costs and maintenance, so to add a little bit of information to that discussion, for an aerated tank, for a 9 person Graf system, and intermittent use the estimate was 2 carbon cartridges at £150 per year plus ~£200 service visit per year. So, an additional £500 annually plus whatever power costs may be. This is not the primary consideration for me as a non-functioning or mal-fiunctioning system would soon consume that much money in call-out costs and aggravation, but I add it here just for the wider knowledge pool. From all of the discussions above, my summary is: Biodisc, not widely recommended due to mechanical elements. Aerated: simple easily maintained, but will need careful management and additional expense if left unused for extended periods. Biorock: maybe, but concerns over depth for gravity feed, consumables, and little/no experience of its use on the site. I still have some more calls to make, but at the moment, I would be opting for Graf or similar and building in the additional maintenance costs.

@saveasteading there is a fair amount of first order data on their website, and this video as a high level explanation I didn’t find any detail on the make up of their media, but not sure I would expect them to be explicit on that in a public forum anyway. Seems interesting as it has even fewer moving parts than the Graf system. Ross

Thanks John, We have SEPA approval, so if I chose to change horses at this stage it will require resubmission. Since my last note, and guided by the above discussion, I've had some more conversations with architect and Graf, and the plot thickens. Given the intermittent use, Graf UK recommended that I consider a third system: Biorock https://biorock.com/products/small-sized-systems/ecorock, which if we can manage gravity outflow, can be an unpowered system, and would not need regular dosing as per the Graf One2Pure tank. This approach on one hand is attractive as there are no ongoing running costs, but on the other hand, is it a bit of a retrograde step - it looks like a traditional septic tank with an added aerobic filtration system (filtration media lifetime claimed as <10 years)? Does anyone have experience of the BioRock system? Ross.

@SteamyTea I guess it’s good they had somewhere to go somewhere. Bad news is if they all stayed there together and fostered their collective incompetence. 🥴