Most likely problem on a car of this age is a blocked heater matrix. You say both pipes are hot, but they may both be heating up from the engine block side rather than via a through flow. Try running the engine from cold and check both inlet and outlet pipes regularly. The inlet should heat up quite quickly and the outlet a little slower (since it should be losing heat to the matrix). If they both heat up slowly I suspect a blocked matrix in which case you will need to try and flush it out. You will need to drain the cooling system and if possible disconnect the matrix pipes and then flush through with a hose pipe - preferably both ways to dislodge the sediment. While you're at it you may as well flush through the radiator as well and then renew the antifreeze when you re fill. If that doesn't cure it try and check the flaps/ducts that control the airflow through (or not through) the matrix to make sure they are moving. If they are seized in the 'cold' position you'll never get heat out! Good luck.
Richard
December 2008
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix cars.