26 May 13 11:27 AM

Suggests to me the controller is faulty. Solar controllers are fairly generic things, various inputs that tell the pump what to do (with extras like frost protection and back element control). Looks l......read more

26 May 13 11:15 AM

Sorry, this doesn't make any sense. An electric element HAS to have a thermostat. The only times I've heard of short lives of elements is when the water quality is questionable. To get any sort of eff......read more

21 May 13 10:18 PM

Meant to say the hot water heat pump controls could divert warm water to the slab when necessary. JK...read more

21 May 13 10:17 PM

Is the internal temperature of the house designed to stay reasonable all year round without even minimal energy fed into the floor via pipes in the slab? I can't see how it will. I'm not deriding anyt......read more

9 May 13 8:16 PM

Doubt it very much. Even if the heat pump was massively oversized and the circulating pump too small (which results in a large temperature rise) nothing significant would happen. Ideal temp rise is ar......read more

6 May 13 4:05 PM

How do you heat water in winter? A backup solar element will use a lot of power. JK...read more

23 Apr 13 5:21 PM

Just as a matter of interest what form of heating do you suggest for a new home? If not underfloor, why not!? JK...read more

4 Apr 13 10:25 AM

I would request a detailed breakdown from Wellington Electricity, a request for money looks like some sort of scam. I suspect it is their way of charging you, so they can pay you for the privilege of ......read more

31 Mar 13 11:12 AM

Of course a washing machine can be used off grid, as long as it the correct voltage it will be fine. Matthew Whitley is being completely unhelpful, either not understanding that "alternative powe......read more

23 Mar 13 7:36 AM

No, you won't have to make any changes. The solar system will operate exactly the same with mains pressure as low pressure. JK...read more

1 Mar 13 9:47 AM

Super insulated houses (ie Passivhaus) use proper mechanical ventilation. This means a heat exchanger so warm wet air being removed from the house transfers it's heat to the incoming air. This is not ......read more

28 Feb 13 1:10 PM

A standard concrete slab provides all the thermal mass you need - as long as you fit pipes for underfloor heating. If you have a well insulated house you will be able to fit a smaller hot water heat p......read more

16 Jan 13 3:50 PM

Radiators, which are really convector heaters, will work over a wide range of temperatures. However the smaller the radiator the higher the temperature required. Hence heat pumps can be used with radi......read more

14 Jan 13 9:09 AM

Without any shading to north facing windows the air temperature will easily get too hot in summer, regardless of the house construction. 600 eaves work reasonably well in a single story house, provisi......read more

11 Jan 13 4:18 PM

I agree with skamp - could get very hot in summer. If you do need some heating in winter it will be a simple matter of attaching a hot water heat pump to the underfloor pipes. Ours range in size from ......read more

7 Jan 13 9:32 PM

Any number of heat sources can be used for underfloor heating - the trick is to provide the best value for money both in terms of capital cost and running cost. In general low capital cost will mean h......read more

25 Dec 12 8:41 PM

Easy answer - no. A hot water cylinder is simply a store of energy. In a typical family situation a cylinder takes on average 15kWs of energy to heat. Hence PV would have to produce this amount every ......read more

9 Dec 12 1:13 PM

Hi KK - there are a number of ways round a three phase issue. 1. Single to three phase inverter - which I know only from google 2. Fit two single phase units, joined by a low loss header. 3. Fit two s......read more

7 Dec 12 8:45 PM

I can't believe there are still "experts" recommending diesel boilers. Of course an air sourced heat pump will work, it's simply a matter of how much extra sizing to allow. Diesel works out ......read more

17 Nov 12 9:30 PM

A hot water cylinder with a failed thermostat is another possibility. Perhaps a faulty meter. Freezer running all the time? ...read more

31 Oct 12 11:53 AM

e mail john@hydraheat.co.nz or 03 974 3457...read more

19 Oct 12 7:43 AM

I'm generally not a fan of instant gas systems, but that it what I would suggest in this case - run off a small gas bottle. However you would some electricity for this, probably 240 volt. The only pra......read more

19 Oct 12 7:29 AM

A cylinder is a store of energy - hence when solar is installed a large cylinder is essential to obtain a real benefit. Everything is different with a heat pump as savings are simply based on the numb......read more

10 Oct 12 2:59 PM

We lay the pipes directly onto the polystyrene (hence at the bottom of the slab, for a number of reasons. They are less likely to suffer damage; it allows the mesh to be in the top half of the slab wi......read more

8 Oct 12 11:19 AM

I made not have made myself clear with regards to pipe laying. Inslab pipes are usually laid at something like 200mm centres, when done in a spiral pattern this gives a fairly constant temperature ov......read more

7 Oct 12 12:29 PM

Rising energy costs would provide a quicker payback, much as it would for better windows or better insulation elsewhere - hence I don't think it's justified to get hung up on edge insulation to save p......read more

6 Oct 12 8:54 AM

A screed solution doesn't provide much in the way of thermal mass, which means (for various reasons) loss of efficiency if heat pumps are used to heat the water. We know from customer feedback a fairl......read more

4 Oct 12 8:26 PM

By far the easiest method is to avoid laying pipes towards the outer edges of the slab. Yes - you will in theory have a cool strip on the edge of the room but this is not really a problem. This method......read more

3 Oct 12 8:01 AM

Despite recent price increases it's still difficult to compete with grid electricity. All sorts of elaborate systems can be constructed, but even with cheap Chinese stuff any sort of payback may never......read more

3 Oct 12 7:53 AM

Depends what you are trying to do. Personally I think a lot of DVS/HRV kits are largely snake oil, Moisture Master do a proper heat recovery and ventilation system. Heat transfer kits do a reasonable ......read more

24 Sep 12 9:33 PM

Houses are cold in winter because there isn't enough sun - solar underfloor doesn't work. You would need at least a 10kW wetback to power underfloor, I'm not sure they exist - and even then it would b......read more

6 Sep 12 7:25 PM

With free wood it makes sense to go wetback. The decision to make is the backup for this. Electric, gas, solar, or heatpump. As you will have a cylinder there is little point in gas, as gas water hea......read more

6 Sep 12 10:02 AM

Solar, wetback, greenglow, plus a Rinnai - an extremely expensive water heating option. Personally I think wetback systems are vastly overated - and expensive to install with a mains pressure cylinder......read more

31 Aug 12 1:23 PM

Reference underfloor etc. A preheat or buffer tank does not add to the efficiency, chances are it will reduce it slightly. Also a hot water ring main isn't a good idea, and not necessary in this size ......read more

30 Aug 12 5:53 PM

Water will take about 22 seconds! I have a long house, bathroom either end with a heat pump - with 15mm pipe installed the water takes about a second a metre. Don't get talked into a circulating syste......read more

14 Aug 12 10:23 AM

If you don't put pipes in the floor for underfloor heating you will regret it for ever. A warm floor isn't about heating, it's about comfort levels - every one degree drop in floor temperature means y......read more

31 Jul 12 4:45 PM

Trying to do hot water and underfloor with this set up isn't going to work very well as you simply don't have enough storage. Either it will need constant monitoring, or you will run out of hot water,......read more

28 Jul 12 7:51 AM

Just read the report - and the appendix comparing solar to heat pumps. For many households it's clear a heat pump is a better option - and a better option for the environment as well. In real life the......read more

21 Jul 12 8:40 AM

Building a house costs money, both in time (ie labour) and materials. Note also there are significant costs for consents and such like. Hence a house ends up costing an amount to build, and perhaps 1......read more

25 Jun 12 6:33 PM

Guess what? I agree with you, unfortunately I can't change accepted building practice - only provide the most cost effective solution for an existing problem. In round figures a complete underfloor he......read more

25 Jun 12 9:43 AM

It might well be German, but their system hasn't been thought through. If you happen to use a hot water heat pump and store water at 50 degrees, to comply with the 60 degree rule means taking water to......read more

21 Jun 12 8:30 PM

Solar and wetback work well together - but setting it up is a different matter. Mains pressure cylinder with wetback coil. Solar is direct, ie this part is also mains pressure. Wetback coil has to be......read more

15 Jun 12 12:07 PM

If you were building a new house, and an underfloor system also cost $16,000 - (far superior for heating), would you still put a fully ducted system in? If so, please give your reasons. Just curious. ......read more

14 Jun 12 5:48 AM

PVC windows wouldn't make much difference. As you don't have pipes in the slab, which for all practical purposes the only way to distribute heat from one heat pump throughout a whole house, you will h......read more

28 May 12 8:18 AM

The next best alternative to a heat pump, in energy cost terms, is wood. Wood boilers of any sort are expensive, and the wood itself costs about twice as much per kW hr as a good heat pump. What are y......read more

17 May 12 7:16 PM

Obviously copper heat exchangers would be fine. Sorry, didn't realize about the size restriction. You could in theory use some old car radiators - but not sure how you'd join them to water pipes and c......read more

15 May 12 5:59 PM

Yep, rust is the problem. As far as I am aware I don't think you are allowed steel products where potable water is involved. If you want a thermosyphon system to work you will need reasonable surface ......read more

14 May 12 7:06 PM

Go for it - it will work. However - you can't use a steel radiator - it will have to be aluminium if you don't have a coil fitted to the cylinder. JK...read more

13 May 12 10:33 AM

I don't see a problem with any non opening windows - and frankly I don't see much a problem with a lot of opening windows. In the long run perhaps hinges will wear quicker - but how long is the long r......read more

8 May 12 8:17 AM

Most people are dependent on energy companies - a true "off grid" system with no other inputs of diesel or gas is expensive. The trick is to use as little energy as possible for the greatest......read more