Heating System Basics...

[ProDave]

8 minutes ago, epsilonGreedy said:

 

That would be it, bottled LPG prices are silly. I am currently paying £58 for a 47kg bottle to keep the static caravan warm or about £0.60 per litre.

More like £75 here.  At least just for cooking 47Kg lasts over a year.

[Jeremy Harris]

Looks like prices have risen by around 15% or more in the last week or two.  Not just Calor, but others too.  The list I gave is just the energy price, doesn't include LPG tank rental or gas or electricity standing charge (although the electricity standing charge will be paid anyway)

[Mr Punter]

6 minutes ago, Jeremy Harris said:

Looks like prices have risen by around 15% or more in the last week or two.  Not just Calor, but others too.  The list I gave is just the energy price, doesn't include LPG tank rental or gas or electricity standing charge (although the electricity standing charge will be paid anyway)

 

Standard practice at the onset of winter.  Robbing b*stards.

[Jeremy Harris]

Looking around, the size of the LPG heating market doesn't seem huge, an estimated 150,000 UK LPG heating installations, out of a housing stock of around 27,227,700 so only about 0.55% of the whole UK household heating market.  That may have a bearing on pricing, especially as it seems that all the suppliers put their prices up around the same time (from what I've just seen both Calor and Flogas have done this).

[ProDave]

At our old house that used oil, I watched the price througout the summer at https://www.boilerjuice.com/heating-oil-prices/  It was almost always cheapest about late August which is when we filled the tank for the winter.

[Jeremy Harris]

There's an oil club that operates in our village.  Run by a group of volunteers, they collect details of oil requirements from anyone that wants to join, then put out a request for tenders to a few suppliers, based on the total volume.  They seem to get a pretty good price, from what I can gather.

[Nick1c]

I received rough costs for the Zehnder radiant panels last week:
 

”I believe the radiant heating panels can provide 60W/m2 of cooling and 100W/m2 for heating. The cost involved would cover a dehumidification unit £2000, cooling wet pipework connections £3000, controls £1000 and panels £2000. Installation of panels £1000”

 

This is for 80-90m2, I am sure the costs can be worked on to a degree, but not to the point where they become sensible. 
My first floor affordable options are UFH using a biscuit mix (this would allow a degree of management of soar gain, the SE has asked for £1,000 to calculate if a 160mm CLT floor with maximum spans of less than 3.5m can support it!), or to make provisions for some electric heaters if they prove to be necessary & hope cooling isn’t needed - we will have 300mm walls/400mmroof warmcell, 3G & a passive slab, the majority of the glazing faces N, any that doesn’t will have external blinds. 

 

 

[Jeremy Harris]

100W/m² seems way OTT for a new build, or even a house built any time in the past couple of decades.  Admittedly our heating requirement is lower than average, at around 5 W/m² on average for just the ground floor in the winter (about 21 W/m² worst case, when it's -10°C outside, and we don't have upstairs), but I'd be surprised if any new build needed more than about 30 to 40 W/m².

[joth]

30 minutes ago, Jeremy Harris said:

100W/m² seems way OTT for a new build, or even a house built any time in the past couple of decades.  Admittedly our heating requirement is lower than average, at around 5 W/m² on average for just the ground floor in the winter (about 21 W/m² worst case, when it's -10°C outside, and we don't have upstairs), but I'd be surprised if any new build needed more than about 30 to 40 W/m².

Presumably the quote is per square meter of radiant panel, not per m2 of habitable floor area?

Although that seems very low compared to a conventional radiator.

 

With a quick search I can't tell, are these zenhder panels entirely water to air, or do they have an electric element for heating?

[epsilonGreedy]

1 hour ago, PeterW said:

What’s the current bulk prices now ..? I saw Calor do their usual pre-cold snap hike a couple of weeks ago. 

 

 

Last time I looked into a 2-year contract they (the Humbeside business you suggested) offered 38p per liter fixed for the first 6 months. I have no idea what the effective average rate is over the whole contract.

[epsilonGreedy]

1 hour ago, Jeremy Harris said:

Looking around, the size of the LPG heating market doesn't seem huge, an estimated 150,000 UK LPG heating installations, out of a housing stock of around 27,227,700 

 

 

I wonder if that is based on the count of LPG boilers or bulk tank installations subject to the new'ish Government regulation of the industry? In Lincolnshire a surprising number of people reside in chalets and static caravans on park plots and receive bottled LPG for heating.

[Jeremy Harris]

2 minutes ago, epsilonGreedy said:

 

I wonder if that is based on the count of LPG boilers or bulk tank installations subject to the new'ish Government regulation of the industry? In Lincolnshire a surprising number of people reside in chalets and static caravans on park plots and receive bottled LPG for heating.

 

 

That's bulk tank LPG installations.  No idea how many use bottled gas for heating, but I'd guess it's probably not a very large number, given the very high cost of bottled gas.

[epsilonGreedy]

8 minutes ago, Jeremy Harris said:

That's bulk tank LPG installations.  No idea how many use bottled gas for heating, but I'd guess it's probably not a very large number, given the very high cost of bottled gas.

 

 

One district council my way estimates they have 1400 static caravans used as a permanent residence, for them LPG is the default heating choice. 

 

https://www.e-lindsey.gov.uk/media/5847/CD57-Hidden-Communities-in-Caravans-Project-2011-Sheffield-Hallam-University-and-East-Lindsey-District-Council-/pdf/CD57_Hidden_Communities_in_Caravans_Project_2011_(Sheffield_Hallam_University_and_East_Lindsey_Distr.pdf

[Jeremy Harris]

This quote is out of date (2011) but seems to have the same number of bulk LPG installations, but also gives an estimate for bottled LPG heating:

 

Quote

Although it's a home heating source that's in decline, of Office of Fair Trading (OFT) report estimated that in 2011 there were around 150,000 households using what's known as bulk LPG for heating purposes, while a further 25-50,000 used cylinder LPG.

 

Using the upper estimate that would mean around 0.73% of UK homes used LPG for heating, so still a pretty small market.  Whether that has an impact on price I don't know, but I suspect it may do, as the process of changing from one LPG supplier to another, at least for bulk LPG, seems a bit more onerous than changing oil suppliers.  It seems you can only change bulk LPG supplier once per year, as the new supplier has to agree to purchase the tank from the old supplier.

[joe90]

Going back to bathroom heating, our (near) passive build has electric heated towel radiators In both bathroom and en suite but I put electric UFH in our en suite (both bathrooms have luxury vinyl floors which are not as cold as ceramic floor tiles) they are all on timers and are nice and warm to the feel/touch. Bedrooms have no heating (UFH Downstairs only) but super cold winter days are catered fir by small electric radiators (which have not been used yet).

[Jeremy Harris]

Just now, joe90 said:

Going back to bathroom heating, our (near) passive build has electric heated towel radiators In both bathroom and en suite but I put electric UFH in our en suite (both bathrooms have luxury vinyl floors which are not as cold as ceramic floor tiles) they are all on timers and are nice and warm to the feel/touch. Bedrooms have no heating (UFH Downstairs only) but super cold winter days are catered fir by small electric radiators (which have not been used yet).

 

 

It's the one thing I wish I'd done, fit electric UFH in the bathrooms.  It's not a major issue, but it is something I miss, as I fitted electric UFH under the tiles in the bathroom at our old house.  It wasn't until we moved in that I realised the difference having the floor just a couple of degrees warmer made to bare foot comfort.  TBH, it's not a major issue, it just means keeping slippers on until stepping into the shower, and having a reasonable bath mat to step out on to, but it niggles me that I didn't think to do it.

[ProDave]

We have wet UFH in our bathroom and en-suite.  It works to take the chill off the floor but it is not very effective at heating the room.  At first I thought it was the spreader plate system we used.  But the very same spreader plates in the utility room work very well.  I now thing the problem may be the tanking membrane that went down before the tiles is a damned good insulator?

[TerryE]

10 hours ago, ykhan16 said:

@TerryE That sounds sensible. Can you confirm you didn't put UFH in your upstairs bathroom? My upstairs will be carpeted but will tile the bathroom and ensuite so would worry about them being cold to feet and slower drying. Many thanks!

 

Our ensuites are all wet-rooms.  No UFH upstairs.  The floor temp is typically around 22°C so they aren't really cold.  The pan area gets hotish after a few secs of shower stream.   We do use a mat in front of our ensuite toilet to keep the old tootsies warm when sitting contemplating. ? 

 

I personally don't see the need for UFH in the ensuites but this is a personal preference.

 

We also have a 30cm window blade in each of our 3 ensuites.  The main reason is that we decided not to bother with any shower screening so we do end up with some water splash on the flat area of floor outside the area of the tray area.  It's a 30sec job to run the blade over the floor and shower walls after a shower, and (with the help of the MVHR extract) the room is pretty dry 5 mins later -- and absolutely no mould anywhere. 

[Bitpipe]

17 hours ago, Jeremy Harris said:

 

 

It's the one thing I wish I'd done, fit electric UFH in the bathrooms.  It's not a major issue, but it is something I miss, as I fitted electric UFH under the tiles in the bathroom at our old house.  It wasn't until we moved in that I realised the difference having the floor just a couple of degrees warmer made to bare foot comfort.  TBH, it's not a major issue, it just means keeping slippers on until stepping into the shower, and having a reasonable bath mat to step out on to, but it niggles me that I didn't think to do it.

 

We did this as a very, very last minute thing (fist fix was complete and walls were boarded but not yet skimmed. 

 

Our extremely patient sparky and myself removed the necessary boards and put in conduit runs & back boxes for power and stat to the floor, the controller and a switched fused spur for each bathroom.

 

I bought cheap (but decent) Warmstar mats off eBay and the tiler put down the 9mm insulated boards, mats and covered with two part laytex ahead of tiling. Tested & logged the mats with a multimeter at each stage (rolled up, unrolled and installed). The little battery operated alarm box (£10) is good for peace of mind while the tiles are being laid as it will buzz if the mats are damaged (short between N/L or N/L and E). It was another month or so before they were powered up - I suppose we could have stuck a plug top on each one just to test them.

 

Does not heat the bathroom but takes chill off floor. 

[Pete]

2 hours ago, Bitpipe said:

 

We did this as a very, very last minute thing (fist fix was complete and walls were boarded but not yet skimmed. 

 

Our extremely patient sparky and myself removed the necessary boards and put in conduit runs & back boxes for power and stat to the floor, the controller and a switched fused spur for each bathroom.

 

I bought cheap (but decent) Warmstar mats off eBay and the tiler put down the 9mm insulated boards, mats and covered with two part laytex ahead of tiling. Tested & logged the mats with a multimeter at each stage (rolled up, unrolled and installed). The little battery operated alarm box (£10) is good for peace of mind while the tiles are being laid as it will buzz if the mats are damaged (short between N/L or N/L and E). It was another month or so before they were powered up - I suppose we could have stuck a plug top on each one just to test them.

 

Does not heat the bathroom but takes chill off floor. 

Quite a few people have mentioned that is does not heat the bathroom but I wonder if this is because of the MVHR system you have fitted as I have a friend who has elec UFH in their kitchen (old house, no MVHR) and that definitely heats the kitchen as you can physically feel the difference when you walk into the room

[Jeremy Harris]

8 minutes ago, Pete said:

Quite a few people have mentioned that is does not heat the bathroom but I wonder if this is because of the MVHR system you have fitted as I have a friend who has elec UFH in their kitchen (old house, no MVHR) and that definitely heats the kitchen as you can physically feel the difference when you walk into the room

 

 

MVHR always cools fresh air fed rooms, unless it is one of the expensive systems that includes additional heating/cooling.  MVHR is also pretty poor at moving heat, as the ventilation rate will typically be very low, maybe one air change every 2 1/2 hours or so, and the heat capacity of air is very low.

 

Our MVHR has a heat pump built in, so it can heat or cool the fresh air supply to rooms, but the maximum output is about 1.5 kW, so about 250 W maximum per room, but it has to be on full boost to achieve that heat output.  Enough for a passive house, but probably not for one built to just meet current regs, I suspect.

[Bitpipe]

51 minutes ago, Pete said:

Quite a few people have mentioned that is does not heat the bathroom but I wonder if this is because of the MVHR system you have fitted as I have a friend who has elec UFH in their kitchen (old house, no MVHR) and that definitely heats the kitchen as you can physically feel the difference when you walk into the room

 

Mainly it's because I put in quite a low power mat (100w/m2) and only have a few m2 coverage in each bathroom, i.e. where you'd normally walk but not under sinks, loos or baths/showers etc.

 

I also keep it at 22 degrees and only have it come on mornings and evenings when the upstairs bathrooms are in use.

 

Those 3 rooms have MVHR extract so any heat in the warm air would be reintroduced in the supply vents in other rooms (MVHR being about 90% efficient at heat recovery), but as Jeremy says the volume of air being moved is pretty low, even in boost conditions.

 

The wet towel rad which runs at about 60 is a much more significant contributor of heat to those rooms but it is also strictly time limited and off altogether for 8 months of the year to avoid overheating.

Edited November 4, 2019 by Bitpipe

[PeterW]

44 minutes ago, Jeremy Harris said:

 

 

MVHR always cools fresh air fed rooms, unless it is one of the expensive systems that includes additional heating/cooling.  MVHR is also pretty poor at moving heat, as the ventilation rate will typically be very low, maybe one air change every 2 1/2 hours or so, and the heat capacity of air is very low.

 

Our MVHR has a heat pump built in, so it can heat or cool the fresh air supply to rooms, but the maximum output is about 1.5 kW, so about 250 W maximum per room, but it has to be on full boost to achieve that heat output.  Enough for a passive house, but probably not for one built to just meet current regs, I suspect.

 

I've got a bit of a random one here where a large (40sqm partial double height) kitchen diner has both extract and intake. Adding to this... its a heated room, and also contains a WBS... 

 

So just doing a quick check, I've got utility (with in slab UFH), downstairs WC (with in slab UFH), and kitchen diner all with UFH which essentially means I've got 52sqm of circa 80sqm heated slab in the extract zone. Then, a bathroom and ensuite totalling 15sqm upstairs both electrically heated with towel rails.

 

Will be interesting to see what  the extract temperatures are running at when its all running properly !

[Jeremy Harris]

41 minutes ago, PeterW said:

 

I've got a bit of a random one here where a large (40sqm partial double height) kitchen diner has both extract and intake. Adding to this... its a heated room, and also contains a WBS... 

 

So just doing a quick check, I've got utility (with in slab UFH), downstairs WC (with in slab UFH), and kitchen diner all with UFH which essentially means I've got 52sqm of circa 80sqm heated slab in the extract zone. Then, a bathroom and ensuite totalling 15sqm upstairs both electrically heated with towel rails.

 

Will be interesting to see what  the extract temperatures are running at when its all running properly !

 

 

When the WBS is going I'd guess the extract temps will be pretty high.  Might be good in terms of MVHR efficiency, as this usually tends to improve a bit as the temperature differential between extract and supply increases.

 

Just looked at ours, and the room temp is 22.1°C, extract is at 22.8°C and the fresh air room supply is 19.8°C.  The unit is on it's normal background ventilation rate, which gives about 1 air change every 2 1/2 hours.  The heat capacity of the air in the house is about 0.114 kWh/K^[1].  The ∆_T between extract and supply is 22.8 - 19.8 = 3 K, so the ventilation heat loss with MVHR is ~ 137 W.  The outside air temperature at the moment is 10.9°C, so the same ventilation rate without MVHR would mean a ventilation heat loss of ~ 565 W, so the MVHR is reducing the house ventilation heat loss rate by ~ 428 W.  If the temps were the same through the whole 24h day, then the saving in heating energy from the MVHR would be ~ 10.27 kWh, so worth recovering.   Put another way, if we didn't have MVHR, then on a day like today we'd be paying around 312% more for heat input to account for the ventilation heat loss.

 

 

^[1] Should be joules, but I would guess most people can relate kWh to cost better, just because we buy energy in kWh, not joules

[ProDave]

We find when we fire up the WBS, if we put the MVHR on "kitchen boost" (which is a slower boost rate than bathroom boost) is does seem to help move heat upstairs.