Am I being taken for a ride with the UFH quote?

[Colin Green]

I had a quote from Nu Heat for a supply only UFH system. There's 78m2 of castellated trays, pipes and screed for down stairs, 60m2 of polystyrene under floor trays and pipes for upstairs. Manifolds, wiring centres, the whole thing. The first red flag is that they've quoted for 12 thermostats. Hall, landing, downstairs WC and utility all get one each. That strikes me as massive up selling. The second is the £12k price tag. I've spent an hour pricing up the parts and have not quite reached half the quoted figure. That leaves £6k+ as their design and sign off fee. It took me a day to learn how to do the calculations, and to estimate heat loss in each room and the required flow temperature on a cold night. (I'm an engineer in a different field) I'd imagine their guy would take a day to inspect and sign off.

For reference, the house is a '70s 4 bed detached. Solid asphalted concrete floors, 50mm cavity wall insulation, loft insulation to a U value of 0.13. Average double glazing. This is the first quote in. We're still waiting to hear back from a second. Nowhere else has answered their phone so far.

Is this a fair price for what they're offering or is my suspicion right that they're trying it on a bit?

 

[Mister Banks]

They must have assumed that each room is an individual zone hence why there are 12 thermostats. This is something that will be in the design so you need to discuss this with them if you want less zones to control.

 

[roguetrader]

Nu heat are expensive, but they will 100% guarantee their product if installed properly.
If you want cheaper, you will find it without issue.

 

[robinbanks]

That leaves £6k+ as their design and sign off fee

And installation?

Edit:

supply only UFH

Oh

Fark me. Hang on while I look up what I paid..

 

[Colin Green]

And installation?

Edit:

Oh

Fark me. Hang on while I look up what I paid..

They say they're geared up to supply DIYers and plumbers who don't know UFH. They send installation instructions aimed at the DIYer, including the exact layout of the pipes.

I'd lift the floors upstairs, fit the plastic pipe throughout. We'll be having a heat pump at the same time, so I'll get the plumber to connect the manifolds to the heat pump, pressurise and test. I'll do the screeding once pressurised.

The installation needs insulation between the joists, with battens and 9mm board between the joists to hold the routed polystyrene boards and pipes. Plus new floorboards upstairs. All that is on top of the £12k.

 

[robinbanks]

I'll rummage out my quote later this eve; it was well before covid so it will be significantly cheaper than modern times but from memory I called in a company called screed.it to do the downstairs piping and screeding; 16mm pipes at 150 spacing in a 40mm anhydrite screed. They fitted the downstairs manifolds and filled with air to pressure, poured screed and supply/only the Heatmiser Neo thermostats and wiring centres. I think it came in at around £20 a square metre for 300 square metres (but 120 of that was for the neighbour).

I fitted the upstairs loops myself, buying pipe and fittings off eBay (PSW and Rimex, they're both still around), because everyone I spoke to said they would put pipes on top of the existing floor then install another floor deck over.
This irked me because I'd already paid for 22mm egger as part of the timber frame and was then being told to overbatten it with 25mm battens and then a network of pipes in alu heat spreader trays and more 18mm boards, because "fitting the pipes to the underside of the existing floor couldn't be done". As no one would fit to the underside I devised a strategy for doing it myself, pipes held in place by spreader plates pinned in with a second fix nailer and insulated after

In terms of flow design, I'm sure you can sit down and work out your loop sizes and flow rates yourself. I didn't bother getting too technical - I took the advice of a plumber who'd done a lot of underfloor; "keep your loops to max 100m, set them all to a litre a minute and then tweak it up and down depending on how warm you want the floor in the rooms". For the most part I haven't altered them and the smallest room (WC) is warmer, but that's quite nice..

I did install the wiring centres and the stats but I don't use them for anything other than fancy thermometers - the single stat in the control unit for the heat pump does everything; the floor is either all on or all off and the flow temp is 28 degrees. The upstairs is naturally cooler in part because the floor is carpeted and part because (imho) spreader plates are crap, but we prefer cooler bedrooms anyway. If you were having a mix of floor coverings and room temp requirements you can use some mix of zoned thermostatic control, mixers on manifolds and flow rate adjustments. I haven't found the need to get so technical; all my loops are open and never close and the whole house generally sits at 19 degrees downstairs and 16 upstairs during the heating season.

 

[Colin Green]

Nu-heat phoned today to follow up on a few things. They explained that UFH needs heating controls per room to comply with regs, like radiators have TRVs. They offered to supply neoStats for the minor rooms gratis so that they can comply with regulations but not at our expense. The guy also pointed out that their systems come with lifetime technical support rather than a few years warranty.

What he wanted was for me to drill into the wall to find out what cavity insulation there was. I found some but don't know what it is. Where we ripped out some old hot air heating duct, there was some exposed thermalite with a 15mm hole drilled in it. There is a very fine white powder in the cavity. Small clumps of it float in the air like snow. Rubbed into my hand the powder stays brilliant white but disappears into nothing it is so fine. Is this blown glass or something else do you think?

 

[muggles]

NuHeat provide a premium service and product at a premium price. They have excellent backup and insurance backed warranties on their designs. Yes, you can buy the kit much cheaper but you'll not get the same support if there's an issue.

 

[robinbanks]

Yeah, but when you can buy the entire kit 4 times over for the same prices, you'd have to make a lot of warranty claims / use of their support for it to seem like value, IMHO

 

[old duffer]

There is of course an alternative, cheaper, easier option to UFH and that is to oversize the room rads and use low temp heating.
Down side is you can't use 10mm pipe to the rads but as you would be replacing them (mostly) then its not an issue.
Use the rinnai zen combi @ around £900 each. Then switch the DHW to a continuous water heater @ £600 so you separate the systems.
or you could just do things the hard, expensive way.....

 

[robinbanks]

I've got completely the opposite opinion of UFH, and I don't think I'd ever install anything else

 

[Colin Green]

We're going for a heat pump. Gas is on its way out and installing a new system seems short sighted. Heat pumps work best at low water temperatures which is why I'm looking at replacing what's there already.

By my calcs, with loft insulation upgraded to a U value of 0.13 and with the rear extension and new porch, the existing rads could support a dT of 30° except the kitchen / dining room. With a dT of 20°, pretty much the whole downstairs falls short. Bigger rads could do the job, but the whole thing is surface mounted microbore. We've have to fit 15mm as a minimum to get the flow, so we need a whole new system. UFH seems like the way forwards.

 

[robinbanks]

Mmm.. and asking an ASHP for dT of 30 isn't going to do wonders for the efficiency

What U are the walls?

 

[Colin Green]

Mmm.. and asking an ASHP for dT of 30 isn't going to do wonders for the efficiency

What U are the walls?

I've found slightly different figures on line for the various elements. They give a U value for the walls between 0.37 and 0.40 - not awful, not great.

My calcs take the concrete floors to be U 0.8, the walls to be 0.4, the roof to be 0.13 and the windows to be 1.6 (or 1.0 where the orangary or porch helps the doors that lead to them. Working out each room individually and summing them, adding a total loss for air changes and assuming zero solar gain, I need 5.1kW continuous to maintain 30°C above the outside temperature. The radiators fitted are almost 18kW at dT50 and more like 5kW at dT20. UFH is the way to go.

Nu Heat came back with £13.5k for the heat pump and tanks, with commissioning and lifetime warranty, but not installation. They picked a 12kW NIBE ASHP which is more expensive than, say, Samsung. There is a healthy fee for lifetime warranty too!