Bemak

I'm in the middle of a refurb and I'm trying to decide whether I go for rads or UFH for the first floor bedrooms. My preference is for UFH to avoid hanging rads but my plumber thinks that rads would be better as they'll heat the space quicker. I don't disagree, particularly as I would be proposing to have the UFH pipework in pregrooved PLY under an engineered timber floor. I appreciate that the reaction time would be slower as the timber floor above the pipework would act as an insulator - but I'm not sure if that would be a major problem as we would typically only have the bedrooms at 19 degrees anyway. Just wondering if anyone has UFH in a similar scenario and how its working out? If you had the chance to redo it, would you go for rads instead?

I hacked a bit of render off a few years ago to see how labour intensive it would be. Found 3 layers of render had been added over time and it was very difficult to remove, often pulling stone with it. So I repaired the patch I removed. The intention is to render the house completely in the end. I had originally looked at dry lining internally but we've opted to go for 40mm of insulating lime render instead. I was told that over insulating internally could be a bad thing as the walls would sweat behind the gutex board.

Thanks for this link. Think this is probably the better solution for us. The reason I ask if MVHR can be run as extract only is because I don't want to run the risk of being sorry after the fact for not installing it. I assume I wouldn't be

Just thinking. A MEV system utilising trickle vents in windows would be a cheap to run solution that would do what I want which is to extract moisture. I'm used to living in older houses to the heat recovery aspect is probably lost on me. Can MVHR units be run as extract only if required?

Thanks John. That's interesting. Hoping to achieve that level of airtightness. I guess once the envelope is sealed we could carry out a test to see where it's at before deciding on MVHR. As you say, I'd probably be happy with a MEV setup. dMEV isn't really an option as I don't want to go coring 600mm thick rubble stone walls. I'm reroofing the house so I'll be able to add vents to the roof for a MEV system

yes we're putting in a new insulated GF slab which should make a big difference. the external walls are sand and cement render unfortunately. we looked into the possibility to taking it all off and replacing it with lime but it's a non-runner because of a) the prohibitive cost and b) as we're in an exposed area in the west of Ireland, lime render doesn't particularly suit the driving rain that we can experience for weeks on end. so the only direction for the walls to breathe will be inwards. we've stripped off the internal render however and thankfully the walls are quite dry as is. I'll install a french drain around the perimeter of the the house as well which should help with moving ground water away from the base of the walls. it's all we can do really

oh absolutely. I'd likely oversize it to be safe

As posted elsewhere, I have started renovation works to an old stone farmhouse (150sqm) which involves the addition of a two-storey extension. We've decided to go down the route of UFH on both floors which will be run with a traditional oil boiler for now. We've allowed provisions for a HP in the future. The heating will be supplemented by a back boiler in a solid fuel stove. As the existing stone walls will be rendered internally with an insulating lime render to allow moisture to escape - I want to install a good ventilation system that will help to extract moisture from the house. The preference is for the unit to go in a warm attic, from which I can duct all the rooms. As the layout of the house is quite simple, the routes are relatively straightforward. In researching MVHR units, I stumbled upon Nilans Compact P2 unit which combines the ventilation system with the HW Tank which has it's own heat pump to generate hot water. On paper it sounds like a nice system - but it might be overkill for my situation. I suspect installing separate systems would be more cost effective. I would be curious to hear peoples thoughts on it, particularly if you installed a MVHR unit in a similar refurb scenario. At this point I wouldn't know which manufacturers would be considered 'premium' and which would be 'budget' so even to get recommendations in that regard would be great.

In the middle of refurbishing an old farmhouse at the moment and am currently working out service routes before the new slab goes in. I'm proposing to locate an external boiler about 20m from the house - the pipework will be 26mm pex pipe (10mm insulation) which will be run inside a 110mm Wavin pipe - all of which will be buried about 600mm below ground level. I appreciate that some element of heat loss will occur along the way - but as we're proposing UFH in the house, the reduced temperature shouldn't affect things too much. Before I lock this in, just wondering if anyone else has done something similar and if so, how has it worked out? Thanks! *update - apologies, I just realized that I posted about this already. Please ignore!*

thanks for the link!

As posted elsewhere, I've embarked on the refurb of an old 2-storey farmhouse. As part of the refurb I'm going to install a MVHR system to ensure that moisture and condensation is adequately dealt with. I'm also installing a new insulated floor slab with a radon barrier and sump. I was going to run the vent from the sump out under the slab and bring it up in a nearby flowerbed to conceal it. The idea is that I would just put a cowl on it and let it vent naturally. However, in a lot of instances locally, the radon vent is brought up to the perimeter footpath and just capped - then, if necessary, the cap can be removed and a duct with a fan can be installed to vent the sump. My issue with that approach is that I don't want the potential to have a vent running up the side of the house when we've been so careful to conceal all the services to date. However, as we are going to be installing a MVHR unit anyway, I assume it's highly likely that we'll never need to vent the radon sump in the future considering the house will be so well ventilated? The reason I ask is I may just revert back to the standard solution of capping it on the footpath as opposed to bringing it up in a flowerbed as currently planned.

thanks for all the replies on this. I've been distracted with demo starting on site. finally! what are peoples thoughts on UFH for upstairs as well?

thanks for this!

I recently came across 'over floor' heating systems which are essentially an underfloor heating system in a 30mm screed - the idea being that the system is much closer to the surface of the floor allowing for quicker response times while generally running at lower temperatures. I spoke to a supplier about it and they said the following which I thought was interesting "the system achieves a typical operating energy reduction of 50% daily compared to heating the same space using Under Floor Heating". "Conservation of energy on a daily basis sets the ground work for affordable heating and sustaining the building, the most significant feature of Over Floor Heating systems is the remarkable increase in comfort created by operating the system using water at body temperature". All sounds great. I'd be curious to hear of peoples experiences using such a system as I wouldn't be opposed to trying it on a refurb I've started.

just a quick query on a detail I want to ensure is correct. i'm planning to construct a cavity wall extension to the side of an existing two-storey farmhouse. the new extension will replace an old stone extension and we've yet to determine if the stone extension was keyed into the stone of the main house. In any case - I was wondering how best to detail the junction between the new blockwork and existing stonework to prevent any water in the stone wall from getting into the inner leaf (as per the crude diagram below). Is a vertical DPC the best bet or is there a better way of doing it?

that's a great point regarding the soak away in the middle of the run. Thanks Nick!

yes I was looking at something similar. An extra bit of lining in the trench like you say will help a lot.

its a personal preference to not see it.

Hi all, In the initial throws of a refurb at the moment and one thing I'm trying to bottom out is the location of the external boiler. The existing house doesn't really have a rear elevation - it's seen on all sides which is making it a bit difficult to locate the best place for the boiler (inside is not an option). I have a shed nearby that would be perfect, but it's 18m from the house. I appreciate that this is quite a distance, but just wondering if I did a deep trench for the pipework and double up on the insulation around the pipes themselves, would it be a viable solution? Just wondering if anyone else has located their boiler a similar distance from their house and what they did to minimise heat loss.

this is my project - sorry have been offline for a while. Just as an update, over Christmas I had a builder friend call and run through the plan of attack. In short, new floor slab with UFH - for the walls we're going to dry line internally with a metal stud set off the wall by 10mm or so. The insulation between the stud will be either a hemp combi jute, or gutex thermoflex. wall will be slabbed with a gutex thermoroom board on a finsa vapourstop. skimmed with a breathable lime render. when we reviewed the floor joists, they weren't too bad. any bad sections were tight to the external wall. so the metal stud approach will also act as a support for the existing floor joists.

Hi All, Hoping to kick off a project I posted about here previously at the end of the year. It's been delayed for multiple reasons but hopefully it will get a bit of momentum in the next few months. House is an old 2-storey farmhouse, 140 years old with 600mm thick rubble stone walls. The house is in good shape considering it's rarely used and structurally very sound. I had been mulling over whether to dig out the slab at all as the existing floors are relatively sound. In the end, I've decided to dig out the existing floor as it will allow me to install UFH, a radon sump and membrane, and insulation. I was talking to a very experienced contractor about it recently as I was concerned about the potential knock-on of digging out the existing floor. He suggested that I keep the excavation to the minimum and suggested a build-up of, 100mm compacted hardcore, blinding, Radon barrier, 150mm insulation, 50mm liquid screen with UFH. 300mm overall. his argument is that the existing subfloor would already be well compacted and that the suggested buildup would minimise the potential of disrupting existing walls. I agree but I just wanted to put it out there to see if anyone has done something similar?

ensure as well that there is adequate fire stopping between the bedroom and garage. I think it needs to be 1 hour from memory.

The alternative is two or three dMVHR units in the vents, like the lunos e60 etc, which would work in tandem to extract/supply air into the house. These look great for completely airtight houses but I'd be curious to know how they work with standard levels of airtightness.

Thanks Peter. Ideally yes but I looked into the ducting for MVHR but we can't make it work for the downstairs rooms. I appreciate that we would be losing the same amount of heat, but wouldn't that be distributed across the vents as opposed to one blast from a PIV system?

Ok so bear with me on this. Existing 70s house, semi-detached, two-storey. Typical condensation issues associated with a house of this nature. I need to core a few extra wall vents to improve ventilation but I was tempted to add a PIV system to help move air also. However my main concern with this kind of system is the potential for cold air/draughts etc. I'm also not keen on the heater element either as it drives the energy consumption way up. As an alternative would it be completely mad to have a extract unit in the attic do the same thing in reverse? i.e. extract air from the house from a central location (first floor landing) which would have the effect of pulling air into the house from "all the nooks and crannys" and wall vents (as opposed to driving it out). That way the draughty element is reduced as it's warm air that's being moved out as opposed to cold air being drawn in? Just putting it out there. Advice greatly appreciated!