Plate heat exchanger for hot water

antoinolachtnai

A relative has an arrangement for heating her hot water from the gas boiler which was installed in the late 80s.

There is

- a regular direct copper cylinder
- a heat exchanger, connected to the boiler loop on one side and on a loop between the top and bottom of the tank on the other (containing the DHW).
- a circulating pump that drives the DHW around the loop.
- a thermostat to switch the circulation pump on when the boiler comes on and to turn it off again when the DHW is hot enough.

The advantage of this is that it has a big heat output, but doesn't require a high performance coil to be put in the tank.

Does anybody install this type of system anymore? Can you get these heat exchangers easily?

DGOBS

Her gas boiler is 25-30 years old.......think it may be due a change

antoinolachtnai

It probably is. But what difference does that make to the heat exchanger?

JohnnieK

I've installed them in Industrial sistuations all right, never seen them in domestic. The heat exchanger usually has a high out put so heats the cylinder quicker. there not cheap, mind you as I say that was industrial not domestic.

DGOBS

Sorry wasn't being smart, just suggesting it may be more cost effective to maybe upgrade the boiler that has combi or hot water priority rather than a 'bolt on' to an aged inefficient boiler

antoinolachtnai

DGOBS wrote: »

Sorry wasn't being smart, just suggesting it may be more cost effective to maybe upgrade the boiler that has combi or hot water priority rather than a 'bolt on' to an aged inefficient boiler

That's alright! It actually works fine, it's a lovely piece of kit. It doesnt need any spares or anything. I was actually considering getting one for my own house.

DGOBS

very inefficient, in comparison 10-25% more fuel consumption than a modern appliance, and if it has a permanent pilot (as I was informed reliably today!) will cost up to €150 a year just to keep the pilot lighting!! I haven't confirmed that calculation though...on my to do list.

Where would you get one for your own house, they aren't sold anymore? secondhand?

I think Plumbe-It in Clondalkin have a plate heat exchanger for connecting stove backboilers to a sealed system.

creedp

DGOBS wrote: »

very inefficient, in comparison 10-25% more fuel consumption than a modern appliance, and if it has a permanent pilot (as I was informed reliably today!) will cost up to €150 a year just to keep the pilot lighting!! I haven't confirmed that calculation though...on my to do list.

Where would you get one for your own house, they aren't sold anymore? secondhand?

I've seen them used with HPs becasue they have a larger surface area that the internal coils in a the DHW cylinder and therefore allow the HP which is limted to 50c to heat the cylinder faster. These ones are simply connected directly to HP. Haven't heard them used with oil/gas burners because of the higher temps of these heat sources.

antoinolachtnai

DGOBS wrote: »

very inefficient, in comparison 10-25% more fuel consumption than a modern appliance, and if it has a permanent pilot (as I was informed reliably today!) will cost up to €150 a year just to keep the pilot lighting!! I haven't confirmed that calculation though...on my to do list.

Where would you get one for your own house, they aren't sold anymore? secondhand?

It's not a boiler. It has no pilot light. It's a heat exchanger. A big lump of copper, basically, with two inlets and two outlets. That's what I'm looking for.

gary71: thanks for the tip. If they don't sell them for the purpose I have in mind, I don't know if I would go ahead with it.

refco

look up swepp heat exchangers they do similar to what you want i think i have seen one used on a solar heating system