Thermal Heat Store question

marcus_h

Dear Money Savers

We have been having trouble with our hot water cylinder, and feel it may be on its last legs. I have wondered about a thermal heat store to replace it.

Our current system is a hot water cylinder, using off-peak electricity. Water pressure is via a Salamander pump, now broken after 2 years. We use night storage heaters, and wood burning stove for heat. We had looked into heat pumps and under floor heating, but it ended up looking too expensive and disruptive.

In the nearish future, I would like to add passive solar and/or PV solar (I had looked into this, but possible overseas posting delayed it) and down the line maybe a back boiler or similar to the stove.

Also, it would be good to install some normal radiators. Currently the cylinder is on the ground floor, and one of the radiators is 3 ft away in the hall – that one seems like an obvious candidate to change. Ultimately the thermal heat store (or whatever) would power four radiators, though if we have to keep one or two of the storage heaters, it would not be the end of the world

It is a 3-bed house, and we are a family of 3.

In the short term, would the thermal heat store be a good solution, especially given the costs of a new pump, maybe cylinder? Would it raise electricity costs in the interim before any of the other heating systems are installed? Given the parameters above, what sort of size of store should I be looking at?

Our plumber has been very good in the past, but when we asked about this, he has gone quiet… Hence my fielding this to the forum

Thanks for any ideas and info!

zeupater

Hi

First question to mind revolves around how much you want to spend and what you are looking to do long term.

From the above, what combination of sources are you looking to use to heat the water .... log burner/biomass?, boiler?, solar thermal?, GCH ?, electricity (immersion) ?, pv solar diversion ?, one or two immersion heaters ? ..... then there's the output - that'd be DHW & space heating connections at a minimum. It's only when you really know what you want to do that you and/or your plumber can make a sensible decision on the cylinder specification as covering all eventualities will simply waste money - that's possibly the main reason why "he has gone quiet" ...

Also consider space as a decent heat-bank can be huge, how huge depends a lot on the inputs/outputs and the load you're going to put on it ... if you currently have a standard size cylinder in an airing-cupboard you will probably lose most/all of the shelves ...

HTH
Z

marcus_h

Hi

<< First question to mind revolves around how much you want to spend and what you are looking to do long term.>>

The initial need is to replace the current system, as it the heating element has broken twice, and the pump has gone. Also, an electric shower downstairs has gone. So looking for a comprehensive replacement. A like for like replacement would be approx. £500, I would imagine. I have seen thermal heat stores for £700-800, and as they don’t need a pump, this didn’t seem too bad, if they will be a good long term bet. We hope to add some other heat sources later, as set out below

<<From the above, what combination of sources are you looking to use to heat the water .... log burner/biomass?, boiler?, solar thermal?, GCH ?, electricity (immersion) ?, pv solar diversion ?, one or two immersion heaters ? ..... then there's the output - that'd be DHW & space heating connections at a minimum. It's only when you really know what you want to do that you and/or your plumber can make a sensible decision on the cylinder specification as covering all eventualities will simply waste money - that's possibly the main reason why "he has gone quiet" ... >>

We would be using immersion heating immediately (probably over this winter, not much longer), with solar next spring, and a back-boiler slightly further in the future. (No gas on our street). We don’t use much DHW – couple of showers, and a small bath for the wee man, plus a bit of washing up etc. At the moment we have storage heaters, but if a system can run hot water radiators, that would be a bonus – the storage heaters are pretty !!!!!!. 2 or 3 downstairs could be fitted fairly easily, more upstairs later with some other work. So the demands aren’t too high. Our plumber hasn’t got close enough to ask what we want yet!

<<Also consider space as a decent heat-bank can be huge, how huge depends a lot on the inputs/outputs and the load you're going to put on it ... if you currently have a standard size cylinder in an airing-cupboard you will probably lose most/all of the shelves ... >>

Well, space should be OK. The current cylinder sits downstairs in a cupboard in the hall (it is about 5 ft from the fireplace, and I believe long ago there was a back-boiler system installed). It is 180 cm tall, and about 45-50 cm diameter, and when working covers our DHW no problem. We could fit a taller cylinder, also wider, but not deeper. The cupboard is all used up already, so no loss there! I guess there is always the attic if the system requires it

So we are really trying to see if the heat store is a good option. Alternatively, if these are expensive to buy, and operate (in the short term, as above, we will just have the immersion) then we can fit a new pump, maybe replace the element again once or twice, until we are in a position to add all the other heats sources. But that seems like a bit of a compromise and waste of money, potentially.

zeupater

marcus_h wrote: »

Hi

<< First question to mind revolves around how much you want to spend and what you are looking to do long term.>>

The initial need is to replace the current system, as it the heating element has broken twice, and the pump has gone. Also, an electric shower downstairs has gone. So looking for a comprehensive replacement. A like for like replacement would be approx. £500, I would imagine. I have seen thermal heat stores for £700-800, and as they don’t need a pump, this didn’t seem too bad, if they will be a good long term bet. We hope to add some other heat sources later, as set out below

<<From the above, what combination of sources are you looking to use to heat the water .... log burner/biomass?, boiler?, solar thermal?, GCH ?, electricity (immersion) ?, pv solar diversion ?, one or two immersion heaters ? ..... then there's the output - that'd be DHW & space heating connections at a minimum. It's only when you really know what you want to do that you and/or your plumber can make a sensible decision on the cylinder specification as covering all eventualities will simply waste money - that's possibly the main reason why "he has gone quiet" ... >>

We would be using immersion heating immediately (probably over this winter, not much longer), with solar next spring, and a back-boiler slightly further in the future. (No gas on our street). We don’t use much DHW – couple of showers, and a small bath for the wee man, plus a bit of washing up etc. At the moment we have storage heaters, but if a system can run hot water radiators, that would be a bonus – the storage heaters are pretty !!!!!!. 2 or 3 downstairs could be fitted fairly easily, more upstairs later with some other work. So the demands aren’t too high. Our plumber hasn’t got close enough to ask what we want yet!

<<Also consider space as a decent heat-bank can be huge, how huge depends a lot on the inputs/outputs and the load you're going to put on it ... if you currently have a standard size cylinder in an airing-cupboard you will probably lose most/all of the shelves ... >>

Well, space should be OK. The current cylinder sits downstairs in a cupboard in the hall (it is about 5 ft from the fireplace, and I believe long ago there was a back-boiler system installed). It is 180 cm tall, and about 45-50 cm diameter, and when working covers our DHW no problem. We could fit a taller cylinder, also wider, but not deeper. The cupboard is all used up already, so no loss there! I guess there is always the attic if the system requires it

So we are really trying to see if the heat store is a good option. Alternatively, if these are expensive to buy, and operate (in the short term, as above, we will just have the immersion) then we can fit a new pump, maybe replace the element again once or twice, until we are in a position to add all the other heats sources. But that seems like a bit of a compromise and waste of money, potentially.

Hi

Is the cylinder vented or unvented - ie do you have a header tank in the loft ? .... I take it that the salamander pump is for DHW to a power shower, not the entire house? - if so, do you want/need to replace it or have mains pressure hot water ? ... if you're looking at 'greening-up' with solar & a biomass/logs back boiler then high pressure DHW is a bit of a waste of the heat you will have banked ... or ... does "they don’t need a pump" mean that you already have/need pressurised DHW and/or have a very low pressure mains water supply ??

Z

marcus_h

Hi Z - thanks for the points.

It is vented, with a water tank in the loft.

The pump does the whole house, though the main issue is the shower. Pressure is very low overall.

It is a good point that the more pressure, the faster you lose what you store. (Our water is heated off-peak at night at the moment, and so we are used to trying to keep the day’s supply as much as possible). The pressure is very low however, and quite annoying.

We are in a very hard water area – that may be of relevance to this as well.

marcus_h

Would a megaflow type system be better for my needs?

Cardew

marcus_h wrote: »

Would a megaflow type system be better for my needs?

A megaflow system is an unvented system that requires good mains water pressure, which your house does not have. The cold water tank in the roof is removed.

http://www.megaflo-unvented.co.uk/megaflo-unvented-faq.php#4

marcus_h

Thanks Cardew. As far as the pressure is concerned then, there is the option of a pump, or the heat store which provides its own pressure. Any other alternatives?

Cardew

marcus_h wrote: »

Thanks Cardew. As far as the pressure is concerned then, there is the option of a pump, or the heat store which provides its own pressure. Any other alternatives?

If your pressure is really low, I would contact your water company with a view to getting them to increase pressure:

http://www.ofwat.gov.uk/households/supply-and-standards/water-pressure/

Water pressure



What is water pressure?

Pressure is the force that pushes water through pipes. Water pressure determines the flow of water from the tap. The amount of pressure at your tap can depend on how high the service reservoir or water tower is above your home, or on how much water other customers are using. The height of your property can also affect your water pressure – properties at the top of a hill may receive lower pressure than properties which are at the bottom of the hill. You should not notice any difference in your water pressure after having a water meter installed.

Low pressure can reduce water flow to a trickle and it will take a long time to fill a kettle or a cistern. Some modern heating appliances and showers will not work below certain pressure levels. You should seek your water company’s advice before installing this type of equipment to check whether the pressure in your water company’s area is sufficient for these systems to operate efficiently.

Low pressure can have a number of causes. For example, when demand for water is high (such as in the morning or early evenings) pressure can be lower than during the rest of the day. There can also be problems during dry spells when people use hosepipes or sprinklers to water their gardens.

Other causes of low pressure can include:
•inadequate pumping facilities
•water mains that are too small
•reduced pressure from the water main as a result of leakage, equipment failures or blocked service pipes

These are the companies’ responsibility.

Pressure that is too high can damage plumbing fixtures, which may cause flooding. The main causes of high water pressure are listed below.
•Trapped air in your water pipes, which can temporarily increase water pressure. Run your taps for a few minutes to release this air.
•Re-configuring the water supply network when water is moved round to wherever it is needed, sometimes changing the supply route. Normal supply will be returned very quickly in most cases.
•You’ve just moved to the area if you are new to the area, your water pressure may feel higher than you were previously used to.

What should I do if I have a problem with water pressure?

If your water pressure is too low, you should check that there is no problem with the plumbing in your property, such as a partially closed internal stop tap (if fitted) or a leak. If you cannot find a problem, contact your water company. They can take pressure and flow measurements and determine whether the problem lies in the company’s or your pipes.

Water companies should make sure that high water pressure does not cause damage to a customer’s property if the customer’s fittings meet normal standards. If you have a problem with water pressure, speak to your water company first.

If you are not satisfied with the company’s response, you can contact the Consumer Council for Water (CCWater) for advice in pursuing the matter.

What are the official standards for water pressure?

The guaranteed standards scheme (GSS) sets out that water companies shall maintain a minimum pressure of water in the communication pipe serving the premises supplied with water of seven metres static head.

marcus_h

Thanks Cardew, didn't realise I could do this.