Heating suggestions?

[MetManMark]

All

Having had success with my first post I thought I would try a second... The property that we are trying to buy has an old central heating system. Whilst many of the rooms have regular radiators (ie white ridged ones prevalent in most homes) they are pretty small for the size of the room. As the place has been used as offices there are some rooms that have radiators in boxes over the doors with electric fans over them not dissimilar to the design you would see in some shops.These have pipes going to them. There is an old combi boiler in the bathroom that is pretty big and I doubt it works.

Our thinking:
Given that the place is listed we can't puncture the fabric of the building without another planning application so we were thinking that we would replace the boiler with another one in the same place.
The house is a big 4 bedroom effort so the boiler would have to have a decent output.
Although there are 3 toilets there is only the one bathroom so not too many showers / baths to run at once so we were thinking about a combi.
We would replace all the radiators and position them sensibly (ie ditching the ones above doors etc) but look to retain some of the original pipework of the system.

Is this a sensible approach? Is there anything innovative or different we could do given that we are starting from new. I am aware of thermal heat pumps etc but to my understanding they are pretty expensive and tend to require electricity so tend to work with PV arrays (which we can't install even if we had the money as the building is listed...).

Any thoughts would be appreciated. Not posting any photos as we don't want to jinx the purchase
Cheers
Mark

 

[Feltwell]

Hi Mark

I'm presuming your new place has a mains gas supply.

My place is probably a similar size - 5 bedrooms over 3 floors, 3 loos but only 1 bath, 2 showers but both are electric. The survey picked up that our gas boiler was old and due for replacement but we thought it would last longer than just 3 days after we bought the place..... :roll:

We were advised by 2 plumbers not to have a combi, and I posted up on a plumbers forum and got a similar response - this was 4 years ago, how much combi's have moved on in since that time I don't know. We were advised that the best system would be a "Megaflo", but that was also "Megabucks" - so we replaced the old, standard boiler with a new, high output condensing boiler that we were advised would be the second best option.

It's been absolutely fine - and with a modern, pre-insulated hot water tank and some careful pipe lagging the water in that tank takes forever to go cold, run the hot tap 24 hours after the last time the boiler was on and the water is still very hot. The airing cupboard is barely any warmer than the rest of the house, such is the standard of the insulation.

The comments we got back from the plumbers forum was that combi's are fine for smaller houses but for a bigger place they tended to struggle.

Others on here have gone down the ground source heat pump route, but as I understand it these are only really effective when used with under floor heating - the water temperature they achieve isn't high enough to use radiators. Other posters will know far more on this subject than I do. You also need a fair bit of land for the trenches, or you have to drill down which adds to the cost.

 

[MdB]

I have a heat pump and love it. If you have any questions then please ask. However..... Unless you are able to insulate the building to modern standards (approx 100mm celotex in floor, walls etc) then I wouldn't recommend it. Heat pumps like to work at low ish temps with underfloor and aren't able to chuck out the heat needed to heat a poorly insulated building which includes most listed buildings.

 

[MetManMark]

Thanks for your replies. A couple of questions:

Feltwell:
So I am assuming that your condensing boiler was one that heats a load of water in a tank rather than a combi (ie on-demand boiler).
Could you point me in the direction of your plumbers forum please?

MdB:
Because we are thinking of ripping out the central heating system we were thinking that this might be the time to install underfloor heating etc if this is sensible. But from what you have said this probably isn't the way forward for us. We have singly glazed windows (we would like to reinstate the internal shutters to help with insulation) and large rooms with high ceilings. The garden isn't massive either so I think that digging down would be necessary I am just interested in more env friendly options - especially if they pay off in the long run.

Cheers
Mark

 

[Pford75]

We switched to an unvented pressurised system - doesn't have a huge impact on the rads, but does make sense when considering showers in bathrooms etc. (ours is a Dualstream). I certainly wouldn't go for a combi unless the house is very small

A new, more efficient boiler might make sense (depending on how old the existing one is)....but I would suggest that investing first in insulation is likely to have a greater impact than ramping up the heating in an (relatively) uninsulated house

 

[Moo]

We opted for a combo boiler in our son's house* because it was occupied by four young people and we knew of old how annoying it could be when the hot water tank ran out of steam, so to speak. With a combo there was constant hot water. It's been let now for about five years to a group of 'young professionals' and the system still seems to be working satisfactorily.
In our own house** we also installed a combo, partly because of limited loft space for a hot water tank. Twelve years on, we're still quite pleased.


* one of those big solid Edwardian terraces - four double bedrooms, a shower room and a bathroom
** only three bedrooms + two shower rooms, but certainly not small.

 

[Feltwell]

Thanks for your replies. A couple of questions:

Feltwell:
So I am assuming that your condensing boiler was one that heats a load of water in a tank rather than a combi (ie on-demand boiler).
Could you point me in the direction of your plumbers forum please?

Yes - it's a condensing boiler that heats water that is stored in a seperate tank, housed in an airing cupboard (in our case a cupboard on the first floor under the stairs to the attic). You need to think of a place to put the tank, they are pretty large - it doesn't need to be that close to the boiler or on the same floor. I think condensing is the only type you can get now anyway - it's the most efficient currently available. Our system is vented and has an indirect cylinder, in other words we have an expansion header tank in the loft and a cold water tank which feeds the hot cylinder, and the hot cylinder contains a coil through which the hot water from the boiler is pumped, transferring it's heat to the water in the cylinder. I *think* this is the most common non-combi type of system but I am no expert! Others on here know much more about heating than I do.

In our case this system coped with a house that initially had no insulation at all, plus single glazed sashes which needed restoring. We've now got some roof insulation throughout (still some work to do), I've put insulation underneath the ground floor rooms that have suspended timber floors, some of the sashes have been restored & draught proofed and some secondary glazing has gone in. Whilst still work in progress this has all made a noticeable difference to the old place!

The plumbers forum was on the Screwfix website but I'm sure there are others.

http://www.screwfix.com/community/community/plumbers_talk

There are a myriad of different heating system types - I'd say your best option is to get a couple of good plumbers round the place to take a look. What suits one house well won't always suit another - for example, for my system you need somewhere appropriate to site 3 seperate water tanks, which are not needed with a combi. A lot of what you will hear is opinion based, the fact is there will be several different systems that will do the job for you. Also consider what else you want to do with the place - if, like us, you're happy to have a decent electric shower then that will make a difference compared to having a very high flow shower that uses the hot water supply. Some showers can empty a hot water tank with surprising rapidity!

If the house has a "conventional" loft, i.e. no attic rooms, making sure the loft is well insulated is a relatively quick and cheap job and will make a big difference to how much heat the house retains. We found tackling the worst of our sash windows made a big difference to those rooms as well. Basic draught-proofing of doors and windows is reckoned to have the best return of all "heat retaining" measures versus the cost & difficulty, and it can be done with very little impact on the original doors and windows.

 

[Penners]

Given that the place is listed we can't puncture the fabric of the building without another planning application so we were thinking that we would replace the boiler with another one in the same place.

I wouldn't necessarily dismiss the idea of re-routing some pipe runs or even relocating the boiler, simply because this might require LBC. If this is going to be your home, then you want to ensure that it's equipped and laid-out as best suits you for the long-term. So, if I were you, I wouldn't compromise on things simply to avoid the short-term inconvenience of waiting for LBC. And remember that a listed building application is free of charge.

But it may not come to that. I suggest you have a chat with the CO and ask whether you'd be allowed to reroute some CH pipes and (if you want to ) relocate the boiler without this requiring LBC.

 

[MdB]

@MdB:
Because we are thinking of ripping out the central heating system we were thinking that this might be the time to install underfloor heating etc if this is sensible. But from what you have said this probably isn't the way forward for us. We have singly glazed windows (we would like to reinstate the internal shutters to help with insulation) and large rooms with high ceilings. The garden isn't massive either so I think that digging down would be necessary I am just interested in more env friendly options - especially if they pay off in the long run.

Our underfloor runs with an inlet temperature of approx 40 degrees and an outlet temperature of 30 degrees so there is only about a 15 degree difference when the room is 20 degrees. You can run hotter from a heatpump but it is far less efficient which defeats the object somewhat. With a gas / oil heated underfloor, I believe the running temperature is quite a bit hotter - something like 50 degrees I think. This means that the floor can output twice the amount of heat into your room so you can survive with twice the amount of heat loss. Our house (4 bed detached) has a heat pump with a 6kW heat output, compare this to the typical 20kW heat output for a gas boiler. We could have had a higher output pump but if we did, it would have heated the underfloor water too high and become inefficient and would short cycle which means it would have switched itself on and off repeatedly to keep the temperature down. As the heat input is low, the house therefore needs to be insulated very well to keep the temperature up. We have therefore insulated well above the current regulations for a new build. On the positive side, our heating bill is currently around £500 a year in electric and I am hopeful to get this down to around £300 when we insulate the back of the house which currently is rather poor.

Using a heat pump with radiators is an issue due to the low temperatures. We have therefore decided not to fit any heating at all upstairs. It is looking like this is an ok decision due to the insulation levels we have.

Small gardens aren't a show stopper for a heat pump as you can drill straight down. It adds about £2k to £3k to the cost, I am told. You can also run air source rather than ground source but I don't know so much about them. Our complete system was £6500 for heatpump, pipes, underfloor system and mini digger hire. We installed everything ourselves which wasn't difficult though hard work to get the pipes in the garden. Off this price we got a £1200 from the government in the form of a grant making the cost about £5300. At the time, we calculated that an oil based system would cost around £4500 so the heatpump wasn't that much more to install. I service it myself once a year and it takes about 10 mins.

 

[Flyfisher]

Yes - it's a condensing boiler that heats water that is stored in a seperate tank, . . . . Our system is vented and has an indirect cylinder, in other words we have an expansion header tank in the loft and a cold water tank which feeds the hot cylinder, . . . . I *think* this is the most common non-combi type of system but I am no expert!

I'm no expert either but we have a condensing boiler running a pressurised system, meaning that there is no need for any tanks in the attic, which can simplify things. It means we rely on mains pressure for the shower (pumps cannot be added apparently), but it was not problem for us because we have good mains pressure. I'm not aware of any inherent strengths/weakenesses in either configuration and ours certainly seems to be effective and efficient.

There are a myriad of different heating system types - I'd say your best option is to get a couple of good plumbers round the place to take a look.

I'd certainly agree with that. CH systems have moved on a lot from the days when you only really had to decide on the type of fuel. There are many other variables these days, which can complicate the decision process.

 

[MetManMark]

Thanks all for the info so far. The house has a pretty big loft which will be filled with insulation and not used apart from as storage - so there would be room for tanks if necessary. We will get heating engineers round to offer their opinion and will probably go for a combi or one that heats a tank hot water. The question was really more around whether there was anything more clever that could be done. Given that there are fairly large singly glazed windows and that the walls are thick brick / stone from what I have read the thermal heat pump option wouldn't be a sensible offer. Just want to think things through as the current heating system needs sorting out and now would be the time to consider alternatives.
Cheers
Mark

 

[robgil]

If i had the money i would install some smart electrical heaters with some solar panels to help keep costs down.
I cannot see oil and gas being a good investment right now with the way prices are going.

 

[MetManMark]

I don't disagree but I don't think we'll be able to get planning permission to fit solar panels on the roof (even though it is big and faces due south) as it is a listed building in a conservation area...
Mark

 

[Moo]

You may well be surprised at the relaxed attitude of the authorities about that - so long as it won't be visible from the road.

 

[robgil]

You dont have to fit them on the roof either , you can put them in the garden.

 

[AMc]

I am aware of thermal heat pumps etc but to my understanding they are pretty expensive and tend to require electricity so tend to work with PV arrays (which we can't install even if we had the money as the building is listed...).

Solar PV to power heating isn't a sensible option - to see the best return you'd want to use the 'free' electricity as its generated and I tend to like to heat my house at night, in winter not in the middle of the day in summer .
You can use large water tanks to store energy but you'd be better with solar thermal panels to do that and again - you'd be pushed to get enough energy on a cold winters day if you covered your garden and roof in panels.
You could notionally offset the cost of an electric heat pump with the generous solar PV feed in tarrif but you'll still reach a problem with solar output vs. consumption.
If you look at the ratings of a largish solar PV installation you're looking at 3KW peak output on a sunny day - compare that to the output of the boiler your looking at replacing which could be anywhere from 4-12KW continuous load on a cold night and you'll see a substantial difference.

We have a pair of Air Source Heat Pumps driving a combination of radiators and underfloor heating - the combined output at 0C is in the region of 20KW. Some of the building is heavily insulated & double glazed and some of it has solid uninsulated walls with double glazing. The house is 5 bed, 5 reception with a large glass vinery. Our electricity bills are around £2500 a year bearing in mind we use wood burners to back up the heating and only heat the vinery to 18C.

ASHP is in my experience at least as expensive as oil and the price of electricity tracks the oil/gas/coal price so it will never get cheaper unless we come up with a revolutionary, cheap, clean way to generate it - at which point we can all turn the heating off and use fan heaters and electric fires

Ground Source Heat Pumps (as MdB has I believe) cost more to install than ASHP but runs more efficiently providing it has been specified and fitted properly.

The general opinion that I found from the Green Building Forum and elsewhere was that if you have mains gas available then a modern condensing boiler is best. I recommend you get the best most efficient gas boiler you can afford based on the facts that greater efficiency will give you lower running costs as gas prices rise and a better built boiler should also last longer reducing the total lifetime cost. Spend money on heavily insulating everything you can without damaging the fabric of the building to reduce the demand - reducing your demand for heating is the greenest thing you can do.
In a modern house it is possible to build to such a tight envelope that a heating system is no longer needed and the house is kept at a comfortable temperature from incidental heat from people and appliances, but you'll never get there in a period property and it would be damaging to almost all period homes to even try.

Good luck with the purchase!

 

[MdB]

Solar PV to power heating isn't a sensible option

I consider Solar PV to be currently environmentally unfriendly due to the energy use in manufacture. I would love to be shown wrong on this but as yet I know of no Solar PV manufacturing plant that uses their own product to power their plant which says a lot. As technology improves, this will change but I don't believe we are there yet.

Financially though they can be worth considering if you are in to subsidy farming. ROI is around 10% I believe with the feed in tariffs available. Just don't kid yourself you are being green.

The general opinion that I found from the Green Building Forum and elsewhere was that if you have mains gas available then a modern condensing boiler is best.

That was our opinion too when we looked into it and even our heat pump supplier agreed.

Spend money on heavily insulating everything you can without damaging the fabric of the building to reduce the demand - reducing your demand for heating is the greenest thing you can do.

Yep, agree with that too.

 

[Flyfisher]

Some good points in the above two posts.

Mains gas is not always available of course, but where it is then it still seems the most economic choice. The running cost is still the cheapest of most fuels and, importantly, the capital cost is very low. Unfortunately, a lot of the 'alternative' technologies have a high up-front cost. I'm sure the situation will change over the next 10-15 years but that's about the life of a gas boiler anyway (maybe a bit more).

All the alternative options are still at the very early stages of their development, which is why the capital costs are so high. It's the classic 'early adopter' phenomenon that anyone who bought a digital camera 10 years ago will be only too familiar.

However, the recently introduced feed-in-tariffs have skewed the game somewhat and it would be interesting to do a pricing analysis basied on a fully-electric heating system based on selling PV-generated electricity during the day at the very high FIT price and buying cheap-rate electricity at night for storage heaters and/or a heatstore.

But, as MdB rightly points out, this is all economic hocus-pocus rather than a truly 'green' solution.

 

[Penners]

as MdB rightly points out, this is all economic hocus-pocus rather than a truly 'green' solution.

Well put, and well explained by all above. What I don't really understand is why this 'economic hocus-pocus' exists at all.

Why, I ask myself, is the Government tempting me to install gadgetry that will feed-in electricity to the grid at (if I understand the equation correctly - which I probably don't!) a unit price far higher than it will earn commercially. If a substantial portion of the population took advantage of the scheme, the cost to the Government would surely be enormous, wouldn't it? Much more than just subsidising the cost of building a new generation of nuclear power plants?

Add to that my ongoing rant about all the money being poured into unpredictably variable wind generation, instead of utterly predictable tidal generation, and I start getting extremely confused.

I dunno - I think I'm just being thick and naive (he said, carefully avoiding the use of the word 'old').

 

[MdB]

I think you are about right Penners. However, the point about the feed in tariffs is that they stimulate the market which hopefully spurs development and hence hopefully technological improvements which change the game. If this works out then this will be a very good thing.

Wind power on the grid at the moment causes surprising effects on the spot price for electricity. More frequently than you might expect (typically in the middle of the night when the wind is high and the demand is low) the price of electricity goes negative. This means that wind farms pay to put electricity onto the grid and (large) users get paid to use that electricity. It is economic for the wind farm people as the feed in tariffs mean that they still make money.

In the long term, I can see this crazy situation changing as users of electricity shift their usage patterns so as to take advantage of the free or better electricity.