OldSpot

I had a look through prior to posting here. Reading the definitions, on page 6, it cites "Hot water storage system means a vessel for storing: a. heated wholesome hot water or softened wholesome hot water for subsequent use b. water that is used to heat other water together with any ancillary safety devices described in paragraphs 3.10 and 3.11 of this Approved Document and all other applicable operating devices." Which is slightly confusing. If you use a coil to heat the buffer tank and then draw the water directly from the tank, the coil passing through the tank is the vessel used to heat the water...but the coil isn't a hot water storage vessel.

Agreed but would G3 come into play in the scenario described?

I understand the requirement for G3 on an UVC but what about with buffer tanks? For example, if you were to fit an indirect buffer tank where a sealed system boiler (gas/oil) heats tank via coil and then the tank water is used to supply rads or UFH? Would G3 certification then be required? If so (or not) why? Accepting that an expansion vessel would need to be fitted to the top of tank.

@RichardL That's what I did Richard and I concluded the same as you.

This U-value calculator seems to work quite well: Concrete Block Association u-value calculator

@Rob99 Just wondering if/where you sourced from Rob? I've found what appears to be the 20-60C Ivar Uni-Mix from Underfloor Parts but be interested if you found a better place. Cheers

Have you considered running the pipes for radiators in the 40mm build up you have available? Like UFH, radiators can be run from a manifold system. Although the manifold would need 22mm (probably) pipes to it you could then run 15/16mm (or maybe smaller 10/12mm) insulated pipes from the manifold to each radiator. You'd then hide the pipes - which is your concern and I fully understand. This method would also then ensure that you don't have too big a heat loss out of the building.# You could go for electric UFH in bathroom/shower room for background warming of the floor to pimp it up!

Looking at the Profix website it looks like the standard panels have an adhesive backing but the panels with a XPS insulation bonded to them do not. Profix suggest these have to be screwed down in their installation video.

Cheers Nick, much obliged for your reply.

Really? According to Profix they do! You could probably use 5 minute PU adhesive like Lumberjack or Soudal

I'm trying to figure out if I'm being daft or not! Can I use one pump with two UFH manifolds? When I say pump I mean the pump which is attached to the manifold not the CH circulating pump. My reckoning is that if a pump is powerful enough to run for example, a 10 port manifold shouldn't it be also be capable of running two 5 port manifolds? My set up would be to have a pump pack attached to a 5 port, T-off after the pump pack/mix valve with 22mm pipe to feed a 3 port manifold about 3.5 metres away. LoopCad suggests those three loops need a total flow of about 3.5l/min but I don't have the drawing to hand. I could run the six 16mm UFH pipes to the area where the 3 port would go but it would simplify the design and layout if I didn't have to.

Apparently washing the dishes gets rid of it....?

Lots on here have done away with a screed and just have a floor build up as shown in your second post with the floor finish going straight on the concrete slab. If you swapped out some of the hardcore - with 300mm of EPS100 - you'll end up with nominally 1mm of compression. This is based on normal domestic loading of the floor. You'll also get a well insulated floor to boot! Approx. 2/3rds of the compression will be when your (150mm) concrete slab goes down so in reality you'll end up with a "variable" compression of ~ 0.3mm or naff all. I say variable because it will be due to the load imposed by the furniture/people etc living in the property.

Anyone got any recommendations for liquid screed companies in West Oxfordshire area? It's about 110m2.

Thanks Peter, Any reason a simply stainless steel direct cylinder (like this) can't be fitted?

@PeterW Hi Peter, Heat source is an oil (system) boiler and I'm looking at whether/how to use a buffer as I'm concerned about the boiler cycling too much. On the issue of buffers.................I'm actually just going through that now. My current thinking is to use a 150/200l indirect tank to buffer (LoodCad suggests UFH is about 11kW, which correlates reasonably well with my heatloss calcs). It will only serve the UFH. I'm getting a little lost on whether the tank needs to be vented or can be sealed. The coil would be from the boiler but would the UFH side then be classified as unvented (due to tank size) and come under G3 if it was a sealed system? I could alternatively fit a small F&E tank directly above the tank if needed

Cheers Mike

I'm trying to find information on sizing to and from an UFH manifold. Does any one know of a source please? The run is approx. 12m and LoopCad says ~ 15l/min needed in total for the UFH loops. Many thanks.

Thanks both ?- good news

Just wondering if you disconnected (electrically/mechanically) the calibrated actuator before then calibrating the next?

@recoveringbuilder Just wondered if you fitted these Salus auto balancing actuators to the Heatmiser and it worked okay?

Just resurrecting this thread. Couple of quick q's for those who maybe able to help: 1. Clearly a concrete slab has a lower thermal conductivity when compared to a liquid screed and combined with it being thinner SWMBO is a little nervous about a 100m slab with UFH due to the increased warm up times. Is it that bad and what sort of time are we talking about? My heatloss calcs suggest UFH works fine but will need a bit of supplemental heating in the coldest temp which is fine. We plan to have a wood burner anyway. 2. What sort of mix are you using for the slab? (Strength & type - self compacting?) Ours is just a simple floor slab - there are no walls etc built on it and we have 300mm of EPS under it, mainly because it was originally a suspended floor. For anyone think about us using just a screed above it has a ground bearing slab at the bottom.... When I read about the ground temp being a constant 8 or so degrees I wondered if anyone has thought of putting a loop in the ground - similar to a GSHP to provide cooling during the summer....!?

Fly, What oil boiler are you using? I seem to remember Grant saying 40C is the lowest return temp to avoid corrosion?

Might be worth a look in the Barn Conversion section of this forum. I'm sure that others have come across many of the issues you are facing. If you don't have a dpc, with solid walls breathability can be an issue. Having trodden a similar path to you have a read up on limecrete. I haven't used it as it wasn't readily available then but may give you another option.

Do the walls have a DPC?